The Ruling on Combining the Prayers. without a Valid Excuse

Question :

Is it permissible to combine the prayers without any excuse?

Answer:

It is not permissible to combine the prayers without a valid excuse, based upon Allah's Words:
But when you are free from danger, offer prayers perfectly (gamatus-Salat). Verily, the prayer is enjoined upon the believers at fixed hours.

And the Prophet defined the prayer times and fixed a time for each prayer. Therefore bringing forward a prayer from its time or delaying it from its time without an excuse is exceeding the bounds of Allah, the Almighty, the All-Powerful. And Allah, the Most High says:

And whosoever transgresses the limits ordained by Allah, then such are the Zalimun (wrongdoers etc.).

and:
And whosoever transgresses the set limits of Allah, then indeed he has wronged himself.

Therefore, it is required of every person to perform the prayers at their correct time; but if there is some pressing necessity and it becomes difficult for him to pray each prayer at its correct time, then there is no sin in that case if one combines the Zuhr and 'Asr prayers either by bringing forward the 'Asr prayer to Zuhr time, or by delaying the Zuhr prayer until 'Asr time, whichever is easiest for him. And he may combine the Maghrib and 'Isha' prayers, either by bringing forward the 'Isha' prayer to Maghrib time, or by delaying the Maghrib prayer until 'Isha' time, whichever is easiest for him, according to the statement of Ibn 'Abbas, may Allah be pleased with him: "The Prophet combined the Zuhr and 'Asr prayers and the Maghrib and 'Isha' prayers in Al-Madinah, without it being due to fear or rain." He was asked about this and he said: "He wished not to cause difficulty to his people." - That is, that he not cause them difficulty by abandoning the combining of prayers; and this is an indication from Ibn 'Abbas, may Allah be pleased with him, that it is not permissible to combine the prayers, unless not doing so would cause difficulty and hardship. This is what is obligatory, because when a person combines two prayers without legal cause, his combined prayer performed at other than its stated time is not accepted by Allah and is not correct. This is because he performed a deed that is not from the religion of Allah and His Messenger. It has been authentically reported from the Prophet that he said:
"Whoever performed a deed which is not in conformity with this matter (i.e. this religion) of ours, will have it rejected.