Calumniae non temere credundum
Lucian of Samosata
Lucian, Vol. 1. Harmon, A. M., editor. London: William Heinemann, Ltd.; Cambridge, MA: Harvard University Press, 1913.
There are people who, even if they afterwards learn that their friends have been unjustly accused to them, nevertheless, because they are ashamed of their own credulity, no longer can endure to receive them or look at them, as though they themselves had been wronged merely by finding out that the others were doing no wrong at all!