The Prophet (peace be upon him) did not perform any of the obligatory or the supererogatory Salahs in graveyards or in a Masjid (mosque) that has a grave inside; rather, he prohibited this.
It is confirmed that the Prophet (peace be upon him) offered Salah over a deceased person after burial and said Takbir (saying: "Allahu Akbar [Allah is the Greatest]") four times. (Part No. 6; Page No. 261) May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.