Then David hid out in the Cave of Adullam. He sent word to his family, and they sneaked off to join him. As word got out, more and more people came to join David–outlaws and debtors, the disgruntled, those who hated Saul–and he organized them into a fighting force of about 400 men.
Among them was the prophet Gad, who advised David to leave the gave and seek shelter in the Forest of Hereth in Judah. On the way, David stopped in Moab to beg King Mizpah to allow his elderly parents to shelter there (Jesse was 1/4 Moab after all).
Meanwhile, back in Gibeah, Saul heard that not only was David alive, but that he had a band of brigands at his back, he began berating his attendants for plotting against him with David. And how did no one mention that Jonathan and David had sworn loyalty before God? Doeg the Edomite happened to be near enough to hear Saul’s rant, so he came before the king and was all, Er…excuse me, Sire? Um, I happened to see David down in Nob and it pains me to say this, but the priest Ahimelech not only gave that snake in the grass food and a sword, but also inquired of God for him.
So Saul had Ahimelech and his entire family and clan arrested. He accused Ahimelech of conspiracy and treason, but Ahimelech was all, How was I supposed to know that David was lying and that he had rebelled against you? He said it was a secret mission! Who was I to question the king’s right hand? So I helped him. But I’m totally loyal to you, Saul.
Saul was all, Whatever. Guards! Kill him and all the males of his clan! But the guards refused to kill priests. Then Saul told Doeg the Edomite to do it and Doeg was all, With pleasure, Sire! Eighty-five men died that day, and then for good measure, Doeg burned Nob and killed every man, women, child and domesticated animal in it. Everyone of Ahimelech’s clan, except for his son, Abiathar, who fled to David for protection. David mourned and blamed himself, for, he said, he knew Doeg the Edomite would bring trouble when he saw him in Nob.