New Revised Standard Version
David left neither man nor woman alive to be brought back to Gath, thinking, “They might tell about us, and say, ‘David has done so and so.’” Such was his practice all the time he lived in the country of the Philistines.

Contemporary English Version
That's why David killed everyone in the towns he attacked. He thought, "If I let any of them live, they might come to Gath and tell what I've really been doing." David made these raids all the time he was in Philistia.

New American Bible
David never left a man or woman alive to be brought to Gath. He thought, “They will betray us and say, ‘This is what David did.’ ” This was his custom as long as he lived in Philistine territory.

Douay-Rheims Bible
And David saved neither man nor woman, neither brought he any of them to Geth, saying: Lest they should speak against us. So did David, and such was his proceeding all the days that he dwelt in the country of the Philistines.

And David saved neither man nor woman, neither brought he any of them to Geth, saying: Lest they should speak against us. So did David, and such was his proceeding all the days that he dwelt in the country of the Philistines.

Lest

1 Samuel 22:22 And David said to Abiathar: I knew that day when Doeg, the Edomite, was there, that without doubt he would tell Saul: I have been the occasion of the death of all the souls of thy father's house.

Proverbs 12:19 The lip of truth shall be steadfast for ever: but he that is a hasty witness, frameth a lying tongue.

Proverbs 29:25 He that feareth man shall quickly fall: he that trusteth in the Lord, shall be set on high.