س ل فs-l-f
(ن) سَلَفَ يَسْلُفُ سَلَفًا وَسُلُوْفًاsalafa yaslufu salafan wa-sulūfan: to pass before, to go ahead. ﴿عَفَا اللّٰهُ عَمَّا سَلَفَ﴾ (Al-Māʾidah 5:95)
سَلَفٌsalaf (noun, ism dhāt): those who have gone before, predecessors; hence «سَلَفِsalafi ṣāliḥīn» (the righteous predecessors). ﴿فَجَعَلْنٰهُمْ سَلَفًا وَّمَثَلًا لِّلْاٰخِرِيْنَ﴾ (Az-Zukhruf 43:56)
Form IV (ifʿāl) اَسْلَفَ يُسْلِفُ اِسْلَافًاaslafa yuslifu islāfan: to send ahead, to send in advance — i.e. the deeds a person sends forward for the Hereafter. ﴿بِمَآ اَسْلَفْتُمْ فِي الْاَيَّامِ الْخَالِيَةِ﴾ (Al-Ḥāqqah 69:24)This root occurs 8 times in the Quran.