Is it permissible to combine prayers or offer them before their prescribed time due to the unavailability of a place to pray when leaving the house?

A Muslim is permitted to pray anywhere on earth, as the Prophet, peace and blessings be upon him, said: «The earth has been made for me a mosque and a means of purification. So, whoever among my Ummah is overtaken by prayer, let him pray». One can pray in public parks, train stations, bus stations, and on roads. It is obligatory to be keen on performing prayer at its prescribed time, and it is not permissible to pray before its time begins, because the time is a condition for the validity of the prayer. It is not permissible to combine two prayers except due to a legitimate excuse such as illness, travel, or rain. Some scholars have permitted it out of necessity, provided that it is not taken as a habit.