Matthew 3:33-37 says:

"Again, you have heard that it was said to the people long ago, 'Do not break your oath, but keep the oaths you have made to the Lord.' But I tell you, Do not swear at all: either by heaven, for it is God's throne; or by the earth, for it is his footstool; or by Jerusalem, for it is the city of the Great King. And do not swear by your head, for you cannot make even one hair white or black. Simply let your 'Yes' be 'Yes,' and your 'No,' 'No'; anything beyond this comes from the evil one.

I have a great friend (out of state) who has helped me beyond measure. He is a giving person and has a heart for God. He has stepped out in faith to do something big for God. He asked some "Christians" to help him in his ministry. Several jumped on board and he made plans accordingly. Then one big giver backed out at the last minute. This has sent my friend in a tailspin. The same person who backed out on him tried the same thing with me a few years ago but I won't go into that now. All is forgiven. But my friend is stuck. Here is a direct quote:

I have just gotten stuck too many times for trusting Christians.

That is sad! Jesus said our yes should be yes and our no, no. If we can't trust each other who can we trust. I am saddened by the lack of integrity I see in some believers. What a horrible testimony this is for the church! Please pray for my friend.