I am given to understand that Mu'awiya has been corresponding with you. Beware, he wants to make a fool of you, to blunt your intelligence and to harm your self-respect. Remember that it is Satan which will attack an imprudent and incautious Muslim from behind and from right and left so that finding him unwary and unwatchful, it may overpower him and may enslave his reasoning.
The fact is that during the Caliphate of Caliph Umar, Abu Sufyan unwisely gave utterances to something which was unjustifiable and unreasonable. It was one of those evil suggestions of Satan which are not only an insult to a self-respecting man but which cannot help in proving the descent (according to the laws of Islam) or in legalizing the heritage. The condition of a man claiming such a lineage is that of a gate crasher in a party from which he may be thrown out with humiliation.