With reference to the Hadith #, 1633 of Sahih Muslim quoted as follows,
Ibn 'Abbas reported that the Messenger of Allah ( صلی اللہ علیہ وسلم ) combined the noon prayer with the afternoon prayer and the sunset prayer with the 'Isha' prayer in Medina without being in a state of danger or rainfall. And in the hadith transmitted by Waki' (the words are): I said to Ibn 'Abbas: What prompted him to do that? He said: So that his (Prophet's) Ummah should not be put to (unnecessary) hardship. And in the hadith transmitted by Mu'awiya (the words are): It was said to Ibn 'Abbas: What did he intend thereby? He said he wanted that his Ummah should not be put to unnecessary hardship.
I was unable to find the proper way to offer combined prayer, please help me in this and provide reference if possible. Thanks.