Stem خَلْفِ has 2 unique word forms and appears 9 times in the Quran.

Word Translation Occurrences
خَلۡفِهِمۡ behind, behind them, (but are) left behind 10
خَلۡفِهِۦ and behind him, behind him 4
خَلۡفِهِۦٓ and after him 2
خَلۡفِهِۦۖ behind it 2