Albert Barnes Commentary 1 Samuel 25:6

"and thus shall ye say to him that liveth [in prosperity], Peace be unto thee, and peace be to thy house, and peace be unto all that thou hast." — 1 Samuel 25:6 (ASV)

That lives in prosperity—The Hebrew is obscure and is variously interpreted. The simplest rendering is, And you shall say thus about (his) life—that is, with reference to his life, health, circumstances, etc.