Undoubtedly, man is greatly unthankful to his Lord.
The human being is unappreciative of his Lord
Indeed, the human is ungrateful to his Lord
Surely man is ungrateful to his Lord
That truly the human/mankind (is) ungrateful/disobedient (E) to his Lord
That most surely man is ungrateful to his Lord
Indeed man is very ungrateful towards his Lord
Surely, man is ungrateful to his Lord
Indeed, man is most ungrateful to his Lord
That ( good for nothing) human being is indeed very ungrateful to his Lord
Verily! Man (disbeliever) is ungrateful to his Lord