דברי הימים א ד:י פירוש: רש״י

and increase my border with territories.

and Your hand is with me that You save me from harm if You will be with me and save me from harm. so as not to grieve me that no injury, pain, or sadness befall me, and he vowed whatever he vowed.

and God fulfilled that which he had requested and he paid his vow. From here proof is brought that when people subscribe to a charity (in public) for a certain cause, they should not vow but give without a vow. Its midrashic interpretation is well known.