Vows.
Archimandrite Nikifor’s Biblical Encyclopedia
In the Old Testament Church, besides the sacrifices to God required by the Law, besides the festival offerings and freewill offerings, there were also votive offerings (Lev. 22:18, 21). Vows were made by believers either in thanksgiving to the Lord for heavenly help received, or in prayer for God’s help. "And Jacob vowed a vow, saying, If (the LORD) God will be with me, and will keep me in this way that I go (to Haran), then this stone, which I have set up for a pillar, shall be