Salaam Alaikum,
Of course. One may visit any of the Prophets and the Companions and any other Tijani saint or brother in tariqa. Please remember that the ziyara in question is the visit that is for spiritual benefit. For the only spiritual benefit that is needed in this tariqa is for Shaykh Tijani and The Beloved Rasool. This is not saying that one cannot visit another wali or muslim for this is something that is from the Sunnah. But this is the visit that is for the sake of ALlah without the intention to receive madad (spiritual support) or knowledge of Allah. It is ok to visit other saints of other turuq for the Sharia, but for Haqiqa it is not.
there is the saying that "If ones freezer is full, what is the need to beg from other freezers" But we visit to give salaam, for respect, for love, and adaab for all of Allah's saints.
From what I know this is for the beginning faqir. Not for the people of Fat'h (Success) For it is known that the big shuyukh of the Tariqa Tijani have visited other saints of other tariqas. Shaykh Hasan Cisse once told me that one day while he was in Cairo with Shaykh Ibrahim Niasse. Shaykh Ibrahim was in the hotel room reclining. Then he started to get up and get dressed. He said "This very moment Imam Shafi (May Allah be pleased with him) came to me and visited me, It is the Sunnah of the Prophet that if one is visited by his brother in Islam, he should return the gesture and visit him also. Shaykh Ibrahim then told the people that were in the room "you small young tijanis stay, while the older ones will go visit Imam Shafi".
Also there is the story that while in Baghdad, Shaykh Ibrahim visited Sultan Awliya Shaykh Abdul Qadir Jilani (may Allah be pleased with them both) at his burial place. and the gate of his qabr was opened and he entered alone. Some have said that if you were present you could hear them conversing with each other and giving salaams and greetings to each other.
Wa Salaam
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It's a high maqam to be humble and open minded about Allah's servants. It is better to see someone as a wali and in reality they are a hypocrite, rather than see someone as a hyprocrite but in reality they are a wali of Allah.-Shaykh Hasan Cisse