لِّيَجْزِيَ الَّذِينَ آمَنُوا
(So that He rewards those who believed - 4)
This sentence is connected with the earlier one: لَتَأْتِيَنَّكُمْ that is, al-Qiyamah or the Doomsday is bound to come and its purpose will be to reward believers and to provide for them the best sustenance from Jannah (Paradise).