Abdullah B Ubayy B Sallul عبدالله بن أبي بن سلول
Formerly a Jew, he is the most famous hypocrite of the Prophet's time. A leading figure of Yathrib, he was about to be crowned a king when the Prophet (saws) migrated into the town. The affair was put off. It hurt him most. For some time he kept low studying the situation while the general population entered into Islam in droves. Finally, he decided to play the hypocrite by professing Islam outwardly. He remained so until his death commanding a large hidden force of similar character. At the time of Uhud when the Prophet marched out with a thousand men to face off the Quraysh , Ibn Ubayy fell off a little out of town with 300 of his followers on the pretext that his advice to stay within the town and resist the invasion had been ignored. When the Muslims met with defeat, someone remarked: “Oh that Ibn Ubayy was with us so he could strike a deal with Abu Sufyan.” On every critical occasion, he invoked troubles of some sort or the other not without mischief in peace times. During the campaign of Tabuk , once again he tried to create a divide between the Ansar and Muhajirun saying, “When we have reached Madinah, the honored ones will throw out the disgraceful ones (i.e., the Muhajirun).” When he died, his son `Abdullah, a true Muslim requested the Prophet (saws) to give him his shirt to bury him in. The Prophet did so and prayed over his funeral although `Umar tried to remind him that Allah (swt) had promised not to forgive the hypocrites even if the Prophet sought their forgiveness seventy times. The Prophet said he would seek forgiveness more than seventy times.