Is it permissible for a Chadian worker to place his mat inside the mosque until his return to his country due to his cramped living conditions?

Mosques are built for prayer and the remembrance of Allah, not for storing people's belongings. Bringing purchased items into the mosque falls under the prohibition of buying and selling within it, as mentioned by some jurists, including Al-Kasani Al-Hanafi. Therefore, belongings should not be placed in the mosque but rather in another location. However, if the question is about a prayer rug laid out in the mosque for prayer, its owner is permitted to retrieve it, unless they intended to donate it as a waqf.