Is it permissible for a traveler to shorten and combine prayers during his stay in Thailand for treatment with his sick mother, and what are the rulings on a traveler's prayer and when is it permissible for him to shorten it?

Whoever intends to reside in a country for four days or more is obligated to complete the prayer, and it is not permissible for him to combine prayers except for another valid excuse that allows combining. Whoever intends to reside for less than four days is permitted to shorten the prayer and is allowed to combine prayers. Whoever does not intend an absolute residence, but rather stays for a need whose end is unknown, he should shorten his prayers for the duration of his stay.