"Then there succeeded them a generation [khalfun]" - Mujahid said: The generation refers to the Christians after the Jews.
Muhammad said: Qutrub mentioned that it is said: A bad successor [khalf] and a good successor [khalf], and khuluf...
﴿فخلف من بعدهمْ خلف﴾ قَالَ مُجَاهِدٌ: الْخَلْفُ: النَّصَارَى بَعْدَ الْيَهُودِ.
قَالَ محمدٌ: ذَكَرَ قطربٌ أَنَّهُ يُقَالُ:
خَلْفُ سوءٍ، وَخَلْفُ صِدْقٍ، وَخَلَفُ