O you who have believed, why do you say what you do not do?
Great is hatred in the sight of Allāh that you say what you do not do. [As Saff:2-3]
I believe many people will be able to relate to this verse as a lot of us have this problem. I know myself I say things and many times the result is that I do not do what I had said I would do. I never knew there was such a punishment for this action and after reading this I thought if Allah (swt) was to hold hatred for me that would be the worst thing that could happen. Due to this reason I am now more careful and only say I will do something if I am very certain it will happen and may Allah (swt) forgive us for what we lack behind in.