Explanation

Bait e Rizwan/Pledge of the TreeIn was made 628/6 AH.

When Prophet Muhammad ﷺ perform the ritual pilgrimage of Umrah but Quraysh denied. Prophetﷺ sent Hazrat Usman ibn Affan as his envoy to meet with the leaders of Quraysh and negotiate their entry into the city. But Hazrat Usman not come back long time, believe that Hazrat Usman had been killed

On this occasion, Muhammad gathered his nearly 1,400 Sahaba and called them to pledge to fight until death and revenge the death of Hazrat Usman