There is promise of a very great reward on obeying Allah and His Apostle, Allah Most High says: -
"And whoso obey Allah and the messenger, then they will be in the company of those on whom Allah has bestowed His Grace, of the Prophets, the Siddiqun, the martyrs, the righteous. And how excellent these companions are!” (IV: 69)
What great rewards Allah Most High promises for obeying and His Apostle which is already a man's duty by reason of his being human. The real values of such great promises will be realised only after death, but if one ponders even now over the troubles of the Plain of Resurrection and the wretched end of the repudiators of Allah and His Apostle, each and every breath of life can pass in conformance to Allah and His Apostle and, thereafter, if one is absolved only from those troubles, afflictions, torture and punishment which have been promised for those disobedient to Allah and His Apostle, only then it is a great success - such a great success that it is impossible to imagine it while living in this world.
May I be sacrificed on Allah's and His Apostle's unlimited affections on mankind, that the human beings may do something for their own advantage and yet may get rewards - and the reward too fixed for them is so great that they would enjoy the Holy Prophet's company in heaven.