'Vow' in the Bible

It happened at the end of four years [that] Absalom said to the king, "Please let me go and pay my vow which I have made to Yahweh in Hebron,

for your servant made a vow while I [was] staying in Geshur in Aram, saying, '{If Yahweh will indeed let me return} to Jerusalem, then I will worship Yahweh.'"