About Making Promises...

Matthew 12:33-37 - The relationship between what we say and what will happen on the day of justice. (Note the relationship between what we say and what is in our hearts.)
Luke 12:3 - Nothing will be hidden.

2 Corinthians 1:16-18 - The need to speak with integrity and to keep our promises. (Note that circumstances beyond our control may at times prevent us from doing what we promised. But we will try to prevent this, if at all possible.)
Psalm 15:4b - He keeps his promise even when it hurts. (Part of the description of the person who can dwell in God's presence.)
2 Corinthians 1:19-20 - Our example: The integrity God has, when he makes promises.
Matthew 5:33-37 - Your word should be so trustworthy that there will never be any question about whether or not you are telling the truth. You shouldn't need to take oaths, in order for others to be willing to believe you. (And perhaps even then they might be wondering if you are telling the truth!)

Ecclesiastes 5:1-7 - The need to be careful in what you promise. (In this passage, the focus is on making promises to God.)
Note the close connection between lots of talking and being a fool! This association is mentioned many times in the Bible - especially in the Proverbs. (Note also Proverbs 10:9 - our tendency to sin when we start talking a lot.)