"Kallanai nambinalum kullanai nambadhe" -- this actually means even if you believe shri krishna who always did mischeives we should not believe vamana, who came as a short man and turned to be the thrivikrama and thereby fooled mahabali. I am astonished that this ancient proverb gives this information about two Avataras of Mahavishnu, Lord Krishna and Lord Vaaman! Thanks!