An-Naba 78:36

a reward and a generous gift from your Lord[10],

[10] Or "a gift adequately calculated"; as a result of their righteous deeds as well as the ample generosity of Allah.

[As] reward from your Lord, [a generous] gift [made due by] account,[1828]

[1828] i.e., as a result of both their own righteous deeds and the limitless generosity of Allāh (subḥānahu wa taʿālā) . Another meaning is "a gift calculated [to be adequate]."

36. A reward from your Lord, an ample calculated gift (according to the best of their good deeds),[2]

[2] (V.78:36) a) Islâm demolishes all the previous evil deeds and so do migration (for Allâh’s sake) and Hajj (pilgrimage to Makkah). (Sahih Muslim, Vol.1, Chapter 52, Page 18).
b) What is said regarding the superiority of a person who embraces Islâm sincerely:
Narrated Abu Sa‘îd Al-Khudri رضي الله عنه: Allâh’s Messenger صلى الله عليه وسلم said, "If a person embraces Islâm sincerely, then Allâh shall forgive all his past sins, and after that starts the settlement of accounts: the reward of his good deeds will be ten times to seven hundred times for each good deed, and an evil deed will be recorded as it is unless Allâh forgives it." (Sahih Al-Bukhari, Vol.1, Hadith No. 40A).
Narrated Abu Hurairah رضي الله عنه: Allâh’s Messenger صلى الله عليه وسلم said: "If any one of you improves (follows strictly) his Islâmic religion, then his good deeds will be rewarded ten times to seven hundred times for each good deed and a bad deed will be recorded as it is." (Sahih Al-Bukhari, Vol.1, Hadith No. 40B).

Requital from thy Lord - a gift in payment -