Is the traveler's prayer valid after performing tayammum due to the bus breaking down, and is it obligatory to repeat it?

Facing the Qibla and fulfilling all pillars and conditions of prayer are obligatory for the validity of prayer, whether one is traveling or resident. If a Muslim is able to perform them while riding in a bus, their prayer is valid; otherwise, it is not permissible for them to do so. An exception to this is in cases of fear of being separated from companions, or harm, or fear for one's life or property; in such instances, it is permissible to pray while riding. The Malikis and Shafi'is state that one should repeat the prayer, while the Hanbalis state that one does not need to repeat it, and this is the more preponderant opinion. Facing the Qibla is obligatory at the تكبيرة الإحرام (opening takbir) for whoever is permitted to pray while riding, and then they pray wherever their conveyance turns. Ablution (wudu') or ritual bath (ghusl) is obligatory for prayer, and dry ablution (tayammum) is not sufficient unless one is unable to use water or water is unavailable.