Can you please advise me what should you read when you visit the grave of family and friend?

All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.

1. The Prophet used to teach his companions to supplicate with this Du’aa' (supplication) whenever they visit the graveyard: “Peace be upon you all, O inhabitants of the graves, amongst the believers and the Muslims. Verily, we will, Allah willing, be united with you, we ask Allah for well-being for us and for you.” [Muslim]

Ibn ‘Abbas said: “The Prophet passed by graves in Medeenah. He turned his face towards them saying: 'Peace be upon you, O dwellers of these graves. May Allah forgive us and you. You have preceded us, and we are following your trail.” [At-Tirmithi]

If one visits a particular grave, he may greet the person in that grave using the same words he uses to greet live persons. In this case he may stand facing the Qiblah letting the grave be between him and the Qiblah. Then he could ask Allah to forgive the buried person.

For more benefit on greeting the dead when passing by a graveyard, please refer to Fataawa 398383 and 306583.

Allah knows best.