Muhammad Ismail al-Mazandarani in his book “ar-Rasail Itiqadiyah” 1/400 during disucussion of marriage Umar and Umm Qulsum bintul Ali ibn Abu Talib, said:

Translation:

“And more correct, (properly) weighted opinion from sound narrations that he (Ali) – peace be upon him, married him (Umar) with Umm Qulsum, but he (Ali) was forced to do that, oppressed, and he feared accusation and that his hand can be cut..”

Like a real nasibi this shia scholar accusing Ali (r.a) in being coward.