Judges 14:12

And Samson said unto them
His thirty companions, very likely on the first day of the feast:

I will now put forth a riddle to you:
a secret, hidden, abstruse thing, not easy to be understood; a dark saying, wrapped up in figurative terms; and this he proposed as an amusement to them, to exercise their wits, which it seems was usual to entertain guests with, and might be both pleasing and profitable:

if you can certainly declare it unto me within the seven days of the
feast;
for so long the nuptial feast was usually kept, see ( Genesis 29:27 Genesis 29:28 ) . If they could find it out; and with clearness and certainty explain the riddle to him within that period of time, which was giving them time enough to do it in:

then I will give you thirty sheets, and thirty change of garments:
that is, every man one of each. By "sheets" he means, as Kimchi and Ben Melech interpret it, a covering of the body in the night next to the flesh, in which a man lies, and was made of linen; meaning either what we call shirts, or bed sheet, and by change of raiment, a suit of clothes worn in the daytime.