The Prophet Muhammad ﷺ used to
go to the graves of the martyrs of Uhd once a year and also recite the verse of the Holy
Qur’an on excellence of patience. The Prophet Muhammad ﷺ used
to pray for them. When the beloved Prophet Muhammad ﷺ passed
away himself, the Khalifs, Abu-Bakr Razi Allah Anhu, Umar Razi Allah Anhu, Usman Razi
Allah Anhu used to do the same thing. [Tafsir Tabari, Tafsir Ibn-Kathir for Quran 13:20, Shaami states and quotes same hadith in Vol. 1, Baabu Ziyaaratil-Quboor]