Reference: I’laam al-Mu’aasireen bi Fataawa Ibn ‘Uthaymeen – Page 425
Question: Is it permissible to visit [the graveyard of] al-Baqee [in Madeenah]?
Response: As for visiting al-Baqee, then without a doubt it has been legislated because therein are the graves of the companions (radhi-yAllaahu ‘anhum) and the [righteous] predecessors of the ummah, as well as [other] righteous and noble [muslims] from the servants of Allaah; [So], just as it has been legislated for us to visit our graveyards, it has been legislated to visit al-Baqee.