That what any one has vowed to God, he must quickly repay
In Solomon: “According as you have vowed a vow to God, delay not to pay it.” Concerning this same thing in Deuteronomy: “But if you have vowed a vow to the Lord your God, I you shall not delay to pay it: because the Lord your God inquiring shall seek it of you; and it shall be for a sin. You shall observe those things that shall go forth out of your lips, and shall perform the gift which you have spoken with your mouth.” Of this same matter in the forty-ninth Psalm: “Sacrifice to God the sacrifice of praise, and pay your vows to the Most High. Call upon me in the day of trouble, and I will deliver you, and you shall glorify me.” Of this same thing in the Acts of the Apostles: “Why has Satan filled your heart, that you should lie to the Holy Ghost, when your estate was in your own power? You have not lied unto men, but unto God.” Also in Jeremiah: “Cursed is he who does the work of God negligently.”
Source: The Treatises of Cyprian (New Advent)