Judges 13:16

And the angel of the Lord said unto Manoah, Though thou detain me, I will not eat of thy bread: and if thou wilt offer a burnt offering, thou must offer it unto the Lord. For Manoah knew not that he was an angel of the Lord.

Cross-reference

Judges 13:23 reveals that the angel's refusal to eat but acceptance of the burnt offering was a sign that God intended to bless them, not harm them.

In Genesis 18:7, Abraham prepares a calf for the angels who eat, contrasting with Judges 13:16 where the angel refuses to eat but accepts a burnt offering.