I do not agree with extremist beliefs of Zayn who is responsible for keeping ummah away from Ahlulbayt , but I want to clarify that it was in the home of a Companion Sulaiman bin Surad may Allah be pleased with him, that supporters of Imam Husain(as) gathered in Kufah , and they wrote letters to Imam Husain(as). But later when they could not support him, they formed a group of repenters called Tawwabun, and fought and were martyred, so the Sunni Companions fought and died for Imam Husain(as). Shia scholars regard Sulaiman bin Surad as a Shia. Here is a narration of that Companion in Sunni book Ibn Majah. It was narrated that Sulaiman bin Surad said: “The Messenger of Allah (ﷺ) came to us and we stayed for three nights without having anything to eat.” https://sunnah.com/urn/1292510
A spiritual Ishmaelite 