Albert Barnes Commentary Judges 13:15

"And Manoah said unto the angel of Jehovah, I pray thee, let us detain thee, that we may make ready a kid for thee." — Judges 13:15 (ASV)

The language of Manoah, like that of Gideon (Judges 6:18), seems to indicate some suspicion that his visitor was more than human. The word rendered "made ready," is also the proper word for "offering a sacrifice," and is so used by the Angel in the next verse. From this, it appears that the Angel understood Manoah to speak of offering a kid as a burnt-offering. Hence, his caution, thou must offer it unto the Lord. (Revelation 22:8; Acts 10:25–26).