Charles Ellicott Commentary 1 Samuel 29:3

"Then said the princes of the Philistines, What [do] these Hebrews [here]? And Achish said unto the princes of the Philistines, Is not this David, the servant of Saul the king of Israel, who hath been with me these days, or [rather] these years, and I have found no fault in him since he fell away [unto me] unto this day?" — 1 Samuel 29:3 (ASV)

These days, or these years. —An indefinite expression of time. The versions have translated it in various ways. The English Version here is literal. The Syriac version uniquely translates it as, “this time, and time, and months.” The Septuagint is not very easy to understand here, but it apparently understood the expression as signifying “two years.” Maurer would translate it as, “who has been with me always, for days, or rather for years.”