A.T. Robertson Commentary Acts 27:34

"Wherefore I beseech you to take some food: for this is for your safety: for there shall not a hair perish from the head of any of you." — Acts 27:34 (ASV)

For this is for your safety (τουτο γαρ προς της υμετερας σωτηριας υπαρχε). Note σωτηρια in sense of "safety," literal meaning, not spiritual salvation. This is the only instance in the N.T. of the use of προς with the ablative meaning "from the side of" your safety, though a classic idiom (Robertson, Grammar, p. 623), an example of Luke's literary style.

Perish (απολειτα). Future middle (intransitive) of απολλυμ (-υω), to destroy. So the oldest MSS. rather than πεσειτα from πιπτω, to fall. This proverbial expression occurs also in Lu 21:18 which see and in 1 Samuel 14:45; 2 Samuel 14:11; 1 Kings 1:52.