The blessed Verse 3 is saying that Great and Everlasting...
The blessed Verse 3 is saying that Great and Everlasting Divine Rewards are in store for you, since you persevere on the Straight Path against such unfounded claims and even set your hopes on their deliverance and salvation without experiencing exhaustion consequent to your endeavors made on the path. The Arabic adjectival form mamnun derives from m-n-n ("sever") connoting endless and everlasting Rewards.
The blessed Verse 4 presents another depiction of the Noble Prophet (S), saying that he possesses great and marvelous nobilities of character, unrivalled purity and sincerity, and indescribable patience, perseverance, steadfastness, and forbearance. He calls people unto obedience to God Almighty, worships Him more than anyone else, forbid people of committing vices, exercises forbearance, providing those harming and hurting him with admonition.
He invokes God Almighty to forgive the sins of those who slander him. He prays to God Almighty to bestow His Guidance upon those who hit him with rocks and cast hot ashes on his head. He is the focal point of love and the springhead of mercy.