40. How to Pledge Properly?
If a person made a mental, even non-verbal, commitment to give tzedakah, this is called, gomar bleibo, and he is obligated to fulfill that commitment.
A common problem that could be caused by this, is that if a person made such a commitment, but the meshulach disappeared from his sight or he can't get hold of the gabbai tzedakah he made this non verbal pledge to.
The solution is to always make these commitments bli neder, or to make a point that these commitments are made in a way that is not a final decision, rather more theoretical. Thus avoiding any Sha’alos and problems.