He rebuked them for their unbelief and hardness of heart

“But later, as the Eleven were at table, he appeared to them and rebuked them for their unbelief and hardness of heart because they had not believed those who saw him after he had been raised. He said to them, “Go into the whole world and proclaim the Gospel to every creature.”” (MK 16: 14-15) 

Our Lord, on one hand, “rebuked them for their unbelief and hardness of heart because they had not believed those who saw him after he had been raised,” but on the other hand, He “said to them, ‘Go into the whole world and proclaim the Gospel to every creature.’” Our Lord didn’t depend on their preaching to be super correct. The Apostle’s mission is based on God’s grace not on their perfection. We were chosen for our missions with our limits, sins and imperfections to put trust in God’s grace, not in our perfection.  

“This is the day the LORD has made; let us be glad and rejoice in it.” (Gospel Acclamation)