וַיַּאֲמֵ֥ן אָכִ֖ישׁ בְּדָוִ֣ד לֵאמֹ֑ר הַבְאֵ֤שׁ הִבְאִישׁ֙ בְּעַמּ֣וֹ בְיִשְׂרָאֵ֔ל וְהָ֥יָה לִ֖י לְעֶ֥בֶד עוֹלָֽם׃ (פ)
And Achish believed David, saying: ‘He hath made his people Israel utterly to abhor him; therefore he shall be my servant for ever.’
Read midrashic interpretation of I Samuel 27:12: and classical rabbinic exegesis.