[He has made it] straight, to warn of severe punishment from Him and to give good tidings to the believers who do righteous deeds that they will have a good reward
English Transliteration
Qayyiman liyunthira basan shadeedan min ladunhu wayubashshira almumineena allatheena yaAAmaloona alssalihati anna lahum ajran hasanan
Tafsir of Verse 2
right, to warn of great violence from Him, and to give good tidings unto the believers, who do righteous deeds, that theirs shall be a goodly wage
(He hath made it) Straight (and Clear) in order that He may warn (the godless) of a terrible Punishment from Him, and that He may give Glad Tidings to the Believers who work righteous deeds, that they shall have a goodly Reward,