He was aware of the selves of the children of the cowardly families.
In this way "The companions of al-Hasan, whom he sent with 'Ubayd Allah, began slipping away to join Mu'awiya's camp. Of course, they were the great figures who belonged to the people of the houses" and their followers. The number of those who deserted from jihad and betrayed Allah, His Apostle, and the grand son of the Apostle of Allah increased to eight thousand deserters. In his book 'Ta'rikh', Ahmad b. Ya'qub has told us: "He (i.e., Mu'awiya) sent to 'Ubayd Allah b.
'Abbas and offered him a million dirhams. So 'Ubayd Allah with eight thousand fighters joined (the camp of) Mu'awiya. Then Qays b. Sa'd renextd him." [2] Yes, (they were) eight thousand fighters of twelve thousand [1] Al-Majlisi, Bihar al-Anwar, vol. 10, p. 114. [2] Al-Ya'qubi, Ta'rikh, vol. 2, p. 191. Roudat al-Shuhada', p. 115. fighters. It was an awful gap that occurred in the army of al-Hasan. It made al-Hasan's army unable to resist sixty thousand fighters from the strong enemies.
Rather, it was a terrible plot that paved the way to that disaster to happen. So 'Ubayd Allah is responsible for that disaster before Allah and history. These men were hasty to create that discord. They thought that if they had done as the paternal cousin of al-Hasan had done, no one would have blamed them. They agreed on this paralyzed idea to justify their deed before the people.
However, the people did not think about their defeat but through its frame coated with gold, namely Mu'awiya's false gold. Then they knew nothing about the glory of the people of the houses but that they broke the covenant they made with Allah and that they sold the religion for the life in this world. The people who deserted al-Hasan were fully aware of his outstanding merits. Still they tried to exploit him to achieve their desires in this world, but he refused that.
Apart from this, when the people deserted al-Hasan and joined the camp of Mu'awiya, they had no confidence in Mu'awiya's promises. For they knew his attitude towards them when he entered Kufa and broke his promise.