In this verse, instead of the word ‘Thawab’ which means reward, Allah U uses the word ‘Mathubah’. ‘Mathubah’ comes from the word ‘Tathwib’ which linguistically is the repetition of the ‘Takbirs’ of the Imam after he has said them during prayers so that people can hear them. And the one who is performing this repetition is called the ‘Muthawwib’. Therefore, ‘Mathubah’ actually means the repetition of an action in a better way than before. It is also derived from the word ‘Thawb’, which means a shirt. When a shirt is taken by the skilled tailor, he will return it in a form that is better than it previously was.

The word ‘Khair’ which means good, is the only word in the Arabic Language that maintains the same form when it is used as a noun and when used as a superlative. So, we cannot say, for example: “Zaid is Akhyar (in the normal superlative form) than Amr”. Rather, we should say, “Zaid is ‘Khair’  than Amr.” Therefore, when one of two things is good but the other is better, we still use the same word, ‘Khair’, to describe it.

The word ‘Sharr’ which means evil, is the opposite of the word ‘Khair’ or good.