It is permissible to combine daytime prayers Zuhr and ‘Asr together and nighttime prayers Maghrib and ‘Isha’ together when the necessity arises.
Sa‘eed ibn Jubayr reported that Ibn ‘Abbaas (may Allah be pleased with him) said: The Messenger of Allah (blessings and peace of Allah be upon him) put together Zuhr and ‘Asr, and Maghrib and ‘Isha’, in Madinah when there was no fear and no rain. I said to Ibn ‘Abbaas: Why did he do that? He said: So that his ummah would not be subjected to hardship. Muslim (705)
It should be noted that the Hanbali madhhab is the most easy-going madhhab concerning excuses that make it permissible to combine prayers together while not being on travel.
It is permissible to combine Zuhr and ‘Asr together at the time of either of them and to combine Maghrib and ‘Isha’ together at the time of either of them. These four are the prayers that can be put together: Zuhr and ‘Asr, and Maghrib and ‘Isha’, at the time of either of them, either the first or the second.
Below, is a list of legitimate Islamic excuses that allows shortening and combining the daytime prayers together and the nighttime prayers together while not being on travel, as it is permissible for the traveller to shorten the four-rak‘ah prayers down to two and to combine the prayers when needed.
1. One who is sick, for whom not combining prayers together will cause hardship.
2. One who is unable to purify himself with water or to do tayammum for every prayer due to sickness.
3. One who is unable to realize the time, such as one who is blind, in a closed building, one who is underground, and the likes.
4. One who is suffering from istihaadah and others who come under the same ruling, such as one who is incontinent and constantly passes urine or emits madhiy, or suffers constant nosebleeds, and the like.
The proof is the hadith of Hamnah, when she consulted the Prophet (blessings and peace of Allah be upon him) about istihaadah, and he said: “If you are able to delay Zuhr and bring ‘Asr forward, then do ghusl and pray Zuhr and ‘Asr together, and then delay Maghrib and bring ‘Isha’ forward, then do ghusl and offer the two prayers together, then do that.”
Narrated by Ahmad and Abu Dawood, and by at-Tirmidhi who classed it as saheeh.
5. In the event of rain that soaks one’s clothes or soaks one’s shoes or body, in the event of ice because the weather will be very cold, and in the case of mud and intense cold wind. It is not permissible to combine prayers together because of drizzle, or because of light rain that does not soak one’s clothes, according to some scholars, because that does not cause hardship.
Al-Bukhaari narrated with his isnaad that the Prophet (blessings and peace of Allah be upon him) put together Maghrib and ‘Isha’ on a rainy night. Abu Bakr, ‘Umar, and ‘Uthmaan did likewise.
6. One who has work that does not allow them to perform each Salah at its designated time, such as physicians, construction workers, students taking board exams, and the likes who have true and genuine hardship.
The first Hadith we related to our beloved Prophet Muhammad (may peace and blessings be upon him) indicated that the main reason for allowing the combination of the prayers while not being on travel, is the existence of hardship, which indicates that the wisdom behind permitting combining the prayers together is to relieve the Muslims of hardship, otherwise, it would not be permissible to combine prayers together while not being on travel.
In summary, If there is a genuine hardship to pray each Salah at its designated time, whether by night or by day, it is permissible to combine prayers together while not being on travel. It is crucial to mention that this permisibility is limited to unique hardships and it should not be a habit and a trend of one’s practice.
Allah knows best.