From Sahih Bukhari Volume 2, Book 20, Number 209: Narrated Salim’s father: The Prophet used to offer the Maghrib and Isha’ prayers together whenever he was in a hurry on a journey. Narrated Ibn Abbas: Allah’s Apostle used to offer the Zuhr and ‘Asr prayers together on journeys, and also used to offer the Maghrib and ‘Isha’ prayers together. Narrated Anas bin Malik: The Prophet used to offer the Maghrib and the ‘Isha’ prayers together on journeys. Volume 2, Book 20, Number 212: Narrated Anas bin Malik: Whenever the Prophet started a journey before noon, he used to delay the Zuhr prayer till the time of ‘Asr and then offer them together; and if the sun declined (at noon) he used to offer the Zuhr prayer and then ride (for the journey).
According to the Hanafi Madhab, it is not permissible to join two Salaats in
one time. Every Salaat must be performed in its prescribed time.
Apparent joining of two Salaats is permissible, not real joining. Apparent
joining is to, for example, delay Dhuhr Salaat until before its expiry time
and perform Asr Salaat immediately upon Asr Salaat time setting in. the same
may be applied for Maghrib and Esha Salaats.
The above quoted Ahaadith may be understood according to the abovementioned
explanation.
and Allah Ta’ala Knows Best
Mufti Ebrahim Desai