Everyone thinks himself perfect in intellect and his child in beauty.

A Jew was debating with a Musalman
Till I shook with laughter at their dispute.
The Moslem said in anger: ‘If this deed of mine
Is not correct, may God cause me to die a Jew.’
The Jew said: ‘I swear by the Pentateuch
That if my oath is false, I shall die a Moslem like thee.’
Should from the surface of the earth wisdom disappear
Still no one will acknowledge his own ignorance.

Saadi Shirazi

http://www.poemhunter.com/poem/ch-08-on-rules-for-conduct-in-life-maxim-17/