Hadeeth Qudsi 22:

On the authority of Abu Sa’id(may Allah be pleased with him), who said that the Messenger of Allah said:

Let not any one of you belittlehimself. They said: O Messenger of Allah, how can any one of usbelittle himself? He said: He finds a matter concerning Allah aboutwhich he should say something, and he does not say [it], so Allah(mighty and sublime be He) says to him on the Day of Resurrection: Whatprevented you from saying something about such-and-such andsuch-and-such? He say: [It was] out of fear of people. Then He says:Rather it is I whom you should more properly fear.

It was related by Ibn Majahwith a sound chain of authorities.