It is prescribed for men who are visiting the Prophet’s Mosque to visit the grave of the Prophet (peace and blessings of Allah be upon him) and the graves of his two companions Abu Bakr and ‘Umar (may Allah be pleased with them), and to send salaams upon them and make du’aa’ for them.
The way in which the grave of the Prophet (peace and blessings of Allah be upon him) is to be visited is that the visitor should come to the grave and face it and say “Al-salaamu ‘alayka ya Rasool-Allah (Peace be upon you, O Messenger of Allah).” Then he should move about a yard to his right and say salaams to Abu Bakr by saying, “Al-salaamu ‘alayka ya Aba Bakr. (may Allah be pleased with you)” Then he should move a little further to his right, about a yard, and say salaams to ‘Umar ibn al-Khattaab, by saying, ‘Al-salaamu alayka ya ‘Umar. (may Allah be pleased with you)”