As Ibn Mas'ood (R.A) said, 

"Indeed Allah looked into the hearts of the servants and found the heart of Muhammad (saws) to be the best of the hearts of His servants and so He chose him for Himself and sent him as a Messenger. Then He looked into the hearts of His servants after Muhammad (saws) and found the hearts of the Companions to be the best of the hearts of the servants. So He made them ministers of His Messenger (saws) fighting for His Deen. So whatever the Muslims hold to be good then it is good with Allah and whatever the Muslims hold to be evil it is evil with Allah." [Ahmad, at-Tayalasee]