Acts 27:34

τοῦτο γὰρ πρὸς τῆς ὑμετέρας σωτηρίας ὑπάρχει, for this is for your safety; because the men when they had been strengthened by a proper meal would be able to do more towards their own preservation.

For πρός with a genitive, meaning ‘in the interest of,’ ‘to the advantage of,’ cf. Thuc. II. 86, ἡ ἐν στενῷ ναυμαχία πρὸς Λακεδαιμονίων ἐστίν.

οὐδενὸς γὰρ ὑμῶν θρὶξ�, for there shall not a hair perish from the head of any of you. The phrase (with a variation between πεσεῖται and ἀπολεῖται) is a proverbial one to express complete deliverance. See LXX. 1 Samuel 14:45, ζῇ κύριος, εἰ πεσεῖται τριχὸς τῆς κεφαλῆς αὐτοῦ ἐπὶ τὴν γῆν. So 2 Samuel 14:11; 1 Kings 1:52; and Luke 21:18.