Is it permissible to combine prayers upon returning home, or to postpone the Dhuhr and Asr prayers until the following day, or to perform tayammum outside the home when water is available, if it is difficult to renew ablution and remove the niqab and abaya to pray on time outside the home?

A Muslim must perform prayer at its appointed time, for Allah Almighty says: "Indeed, prayer has been decreed upon the believers a decree of specified times." It is not permissible to combine the four prayers or to delay a prayer until the next day. Combining the Dhuhr and Asr prayers, as well as the Maghrib and Isha prayers, is permitted only in cases of extreme hardship, and without making it a habit. Tayammum is not permissible when water is available and one is able to use it, for Allah Almighty says: "And if you find no water, then seek clean earth and wipe over your faces and hands." Wudu must be performed on the way [to prayer] and then prayer performed. However, if it is difficult to maintain privacy during wudu, then tayammum is permissible.