All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad, sallallaahu 'alayhi wa sallam, is His slave and Messenger.
There is nothing wrong with combining sometimes Dhuhr and 'Asr prayers or Maghrib and 'Isha’ prayers, but without taking this act as a habit. This is according to the opinion held by some scholars, such as Al-Ash-hab from the Maliki School of Jurisprudence, Ibn Al-Munthir from the Shafi`i School of Jurisprudence, Ibn Sirin, and Ibn Shubrumah. This opinion is proven by the Hadith reported by Muslim on the
authority of Ibn 'Abbas who said: “The Messenger of Allah, sallallahu ‘alayhi wa sallam, combined Dhuhr and ‘Asr prayers and Maghrib and 'Isha’ prayers in Madinah when there was no fear and no rain.” He was asked: “Why did he do that?” He said: “So that his nation would not be subjected to hardship.”
An-Nawawi stated in his commentary on Sahih Muslim: “Some scholars held the opinion that it is permissible to combine prayers for a need while one is not traveling, but without taking it as a habit. This opinion was held by Ibn Sirin and by Ash-hab from the followers of Imam Malik, and was narrated by Al-Khattabi on the authority of Al-Qaffal and Al-Shashi Al-Kabir from the followers of Ash-Shafi`i. This opinion was also narrated on the authority of Abu Is-haq Al-Marwazi and a group of As-hab-ul-Hadith (the adherents of the Prophetic traditions) and was chosen (as the correct opinion) by Ibn Al-Munthir. It is supported by the saying of Ibn 'Abbas : ‘So that his nation would not be subjected to hardship’. So, he did not say that he the Prophet did this due to an illness or anything else.” [End quote]
Allah knows best.