Ecclesiastes 5:4
When thou vowest a vow unto God, defer not to pay it; for he hath no pleasure in fools: pay that which thou hast vowed. When thou vowest a vow unto God, defer not to pay it; for he hath no pleasure in fools: pay that which thou hast vowed.
When a vow is made to God it must be paid without delay, and to fail to pay makes the vower a fool in whom God has no pleasure. It is better not to vow at all than to vow and then fail to fulfill what was promised. A vow is a sacred and binding obligation made to God Himself, not merely to people, as serious as a business note or a human agreement. It must not be made lightly, nor afterward treated as optional, regretted, evaded, or excused as a mistake.
Neglecting a vow or leaving a pledge unpaid is a violation of duty that should trouble the conscience, because everyone must answer to God and settle His claims. Pledges for God's cause, including tithes and offerings made under the influence of God's Spirit, must be fulfilled while the means are available. A promised portion is consecrated to God and is no longer one's own to withhold, and to withhold what is due is unfaithfulness. Neglect leaves His work without the promised means of support.
Even hardship such as crop failure does not excuse abandoning faith, because God can open a way to fulfill the pledge. To cause the mouth to make the flesh sin means to pledge means to God's work and then grumble, murmur, withdraw the pledges, and fall into distrust and suspicion. That course leads to reluctant giving and loss of blessing, while willing faithfulness in returning tithes and offerings honors God with what He has entrusted.
To say before the angel that it was an error means to make excuses that God's servants deceived, pressured, and extorted unjust pledges from the people. But the angel is God's angel present and listening when the vow is spoken, so the words are heard by more than men. God's anger at the voice and destroying the work of the hands means God is angry with those who break their pledges and therefore withholds blessing and the ability to pay them. Breaking vows in this way has no valid excuse and gives triumph to the enemy.
Withholding part of what was vowed while pretending to fulfill it is fraud and hypocrisy, as in the case of Ananias and Sapphira. God will hold people strictly accountable for how they use what He has entrusted to them. The verse also calls for prompt and faithful fulfillment in stopping faultfinding and vowing before God to seek understanding of His Word through prayer.