We are first introduced to David when the navi, Shmuel, is commanded to go to Beit Lechem to anoint a new king, to replace the rejected King Shaul. Shmuel arrives in Beit Lechem, and the elders of the city come out to greet him, nervous at this unusual and unexpected visit, since the elderly prophet had stopped circulating throughout the land. and came to Bethlehem. And the elders of the city came to meet him trembling, and said: ‘Do You come peaceably?‘ (Shmuel 1,16:4)The elders feared that Shmuel had heard about a grievous sin that was taking place in their city. Perhaps he had come to rebuke them over the behavior of Yishai’s despised shepherd boy, living in their midst.
Shmuel declared, however, that he had come in peace, and asked the elders, and Yishai and his sons, to join him for a sacrificial feast. As an elder, it was natural for Yishai to be invited; but when his sons were inexplicably also invited, they worried that perhaps the prophet had come to publicly reveal the embarrassing and illegitimate origins of their brother. Unbeknownst to them, Shmuel would anoint the new king of Israel at this feast. All that had been revealed to the prophet at this point was that the new king would be a son of Yishai.
When they came, Samuel saw Eliav (Yishai’s oldest son), and he thought, “Surely God’s anointed stands before Him!”
But God said to Samuel, “Don’t look at his appearance or his great height, for I have rejected him. God does not see with mere eyes, like a man does. God sees the heart!” 
Then Yishai called Avinadav (his second son), and made him pass before Samuel. He said: “God did not choose this one either.”
Yishai made Shammah pass, and Samuel said, “God has not chosen this one either.”
Yishai had his seven sons pass before Samuel. Shmuel said to Yishai, “God has not chosen any of them.”
The Small One, Left Behind
As Shmuel laid his eyes on Yishai’s eldest son, he was certain that this was the future king of Israel. Tall, handsome and distinguished, Eliav was the one whom Shmuel was ready to anoint, until God reprimanded Shmuel to look not at the outside but at the inside.
No longer did Shmuel make any assumptions of his own, but he waited to be told who was to become the next king. All the seven sons of Yishai had passed before Samuel, and none of them had been chosen.
“Are these all the lads?” Samuel asked. Shmuel prophetically chose his words carefully. Had he asked if these were all Yishai’s sons, Yishai would have answered affirmatively, that there were no more of his sons, since David was not given the status of a son.
Instead, Yishai answered, “A small one is left; he is taking care of the sheep.” David’s status was insignificant in Yishai’s eyes. He was hoping that Shmuel would allow David to remain where he was, out of trouble, tending to the sheep in the faraway pastures.
But Shmuel ordered that David immediately be summoned to the feast. A messenger was dispatched to David who, out of respect for the prophet, first went home to wash himself and change his clothes. Unaccustomed to seeing David home at such a time, Nitzevet inquired, “Why did you come home in the middle of the day?”
David explained the reason, and Nitzevet answered, “If so, I too am accompanying you.”
As David arrived, Shmuel saw a man “of ruddy complexion, with red hair, beautiful eyes, and handsome to look at.” David’s physical appearance alludes to the differing aspects of his personality. His ruddiness suggests a warlike nature, while his eyes and general appearance indicate kindness and gentility. (Footnote:)
At first, Shmuel doubted whether David could be the one worthy of the kingship, a forerunner of the dynasty that would lead the Jewish people to the end of time. He thought to himself, “This one will shed blood as did the red-headed Esav.”
God saw, however, that David’s greatness was that he would direct his aggressiveness toward positive aims. God commanded Shmuel, “My anointed one is standing before You, and You remain seated? Arise and anoint David without delay! For he is the one I have chosen!” 1 Shmuel 16:12
As Shmuel held the horn of oil, it bubbled, as if it could not wait to drop onto David’s forehead. When Shmuel anointed him, the oil hardened and glistened like pearls and precious stones, and the horn remained full.
As Shmuel anointed David, the sound of weeping could be heard from outside the great hall. It was the voice of Nitzevet, David’s lone supporter and solitary source of comfort. Her twenty-eight long years of silence in the face of humiliation were finally coming to a close. At last, all would see that the lineage of her youngest son was pure, undefiled by any blemish. Finally, the anguish and humiliation that she and her son had borne would come to an end.
The Talmud teaches:
Shmuel b. Nahmani said in R. Yonasan’s name: “I will give thanks unto You, for You have answered me” was said by David;
The stone which the builders rejected is become the chief corner-stone; was said by Yishai ;
This is the Lord’s doing, was said by his brothers;
This is the day which the Lord has made, was said by Shmuel. We beseech You O’ Lord, save now! was said by his brothers:
We beseech You O’ Lord, make us now to prosper! Was said by David;
Blessed be he that comes in the name of the Lord, was by Yishai;
We bless You out of the house of the Lord, was said by Shmuel;
The Lord is God, and has given us light, was said by all of them;
Order the festival procession with boughs, was said by Shmuel;
You are my God, and I will give thanks unto You, was said by David;
You are my God, I will exalt You, was said by all of them. Pesachim 119a
King David would have many more trials to face until he was acknowledged by the entire nation as the new king to replace Shaul. During his kingship, and throughout his life, up until his old age, King David faced many ordeals.
King David possessed many great talents and qualities which would assist him in attaining the tremendous achievements of his lifetime. Many of these positive qualities were inherited from his illustrious father, Yishai, after whom he is fondly and respectfully called ben Yishai, the son of Yishai.
During King David’s reign, the nation faced a devastating three year famine, as the navi states: And there was a famine in the days of David three years, year after year; and David sought the face of the LORD. And the LORD said: ‘It is for Saul, and for his bloody house, because he put to death the Gibeonites. Shmuel 2, 21:1
And later, after King David bought the threshing floor from Aravna the Yevusi, to build a Mizbeach to Hashem, which was to become the site of the future Mizbeach of the Beis Hamikdash, the navi states: And David built there an altar unto the LORD, and offered burnt-offerings and peace-offerings. So the LORD was entreated for the land, and the plague was stayed from Israel. Shmuel 2, 24:25
In Slichos we say:
May He who answered David and his son Shlomo in Yerushalayim, answer us.
In what merit was David answered by Hashem? It was undoubtedly from his mother that the young King David absorbed the fortitude and courage to face his adversaries. From the moment he was born, it was Nitzevet who, by example, taught him the essential lesson of valuing every individual’s dignity and refraining from embarrassing another, regardless of the personal consequences. It was she who displayed a lone, silent, stoic bravery and dignity, in the face of the gravest hardship.
It is from Nitzevet that King David absorbed the strength, born from an inner confidence, to disregard the callous treatment of the world, and find solace in the comfort of God’s protection. It was this strength that would fortify King David to defeat his staunchest antagonists and his most treacherous enemies, as he valiantly fought against the mightiest warriors on behalf of his people.
Nitzevet taught her young son to find strength alone in following the path of one’s inner convictions, irrespective of the cruelty that might be hurled at him. Her display of patient confidence in the Creator, that justice would be served, gave David the inner peace, and solace, that he would need, in confronting the formidable challenges in his life. Rather than succumb to his afflictions, rather than become the individual who was shunned by his tormentors, David learned from his mother to stand proud and dignified, feeling consolation in communicating, alone, with God in the open pastures. Such was the background to the songs of David, sweet singer of Israel.
She demonstrated to him, as well, the necessity of boldness while pursuing the right path. When the situation would call for it, personal risks must be taken. Without her bold action in taking the place of her maidservant that fateful night, the great soul of her youngest child, David, the forebear of Mashiach, would never have descended to this world.
The soul-stirring psalms composed by King David in his greatest hours of aloneness, eloquently describe his suffering and heartache, as well as his faith and conviction.
The medrash states, Why did David think of praising God with his soul? He said “The soul fills the body and God fills the world, so let the soul which fills the body praise God who fills the world. The soul carries the body and God carries the world … The soul is one and alone in the body, and God is one and alone in the world.
The book of Tehillim gives a voice to each of us, and has become the balm to soothe our wounds, as we, too, encounter the many personal, and communal hardships of life in galus-exile. Tehillim is an expression of our aloneness in our relationship with the Aloneness of God. In that merit, david wa answered by Hashem.
As we say Tehillim, our voices mesh with Nitzevet’s, with King David’s, and with all the voices of those past and present who have experienced unjustified pain, in beseeching our Maker for that time when the “son (descendant) of David” will usher in the era of redemption, and true justice will prevail.
 Abarbanel 1:16
A short while after this coronation feast, David was instructed by his father to visit Eliav at the battlefield. A war with the Philistines was imminent, and Eliav lashed out in anger at David. This tendency to anger disqualified Eliav now from the throne. (This event occurred after David was anointed as king. However, according to the commentaries, it is possible that they didn’t understand the implications of the anointing, assuming that Samuel had designated David as a new student in his school of prophecy. Though this was an honor, and an act that would validate David’s lineage, only once David actually became king over the entire nation did his brothers realize his true greatness.)
 Malbim Shmuel 1, 16:12
 Breishis Rabbah 63;8
 Vayikra Rabba 4;8
This essay is an excerpt from Rabbi Roll’s book, Alone Against the World. http://www.feldheim.com/catalogsearch/result/?q=yisroel+roll