Is fulfilling a vow (Nidhr) to walk to the Prophet's Mosque or Al-Aqsa Mosque obligatory?

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Fulfilling a vow to walk to the Prophet's Mosque (Masjid an-Nabawi) or Al-Aqsa Mosque is obligatory. This view is held by Malik, Al-Awza'i, Abu Ubayd, Ibn al-Mundhir, and one opinion of Ash-Shafi'i. The evidence for this obligation is the saying of the Prophet, peace be upon him: "No journey should be undertaken except to three mosques: Al-Masjid al-Haram, this mosque of mine (the Prophet's Mosque), and Al-Aqsa Mosque." Since Al-Aqsa is one of these three mosques, a vow to walk there becomes binding, similar to the vow to walk to Al-Masjid al-Haram. Furthermore, every act of obedience that can be made obligatory by a vow, even if it is not obligatory by default, becomes binding upon making the vow, such as visiting the sick or attending funerals.