Majmu' al-Fatawa - Ibn Taimiya - (23/389)

He was asked:

Is it permissible to pray behind an imam who leads the prayers at two mosques?

He answered:

If a regular imam can be appointed for each mosque, it is not proper to appoint one imam for two mosques. If he leads the prayer in two places, scholars differ over the validity of the second prayer for those praying behind him to fulfil their obligation. The position of Abū Hanīfa, Mālik, and Ahmad, according to one of the two reports from him, is that the congregation of the second mosque has not discharged its obligation. And Allah knows best.

He was asked:

May someone offering an obligatory prayer pray behind someone offering a voluntary prayer?

He answered:

This is permissible according to the stronger of the two scholarly views. This is the position of al-Shāfi‘ī and of Ahmad, according to one of the two reports from him.

وَسُئِلَ: عَنْ إمَامِ مَسْجِدَيْنِ. هَلْ يَجُوزُ الِاقْتِدَاءُ بِهِ؟ أَمْ لَا؟ . فَأَجَابَ: إذَا أَمْكَنَ أَنْ يُرَتَّبَ فِي كُلِّ مَسْجِدٍ إمَامٌ رَاتِبٌ فَلَا يَصْلُحُ أَنْ يُرَتَّبَ إمَامٌ فِي مَسْجِدَيْنِ فَإِذَا صَلَّى إمَامًا فِي مَوْضِعَيْنِ فَفِي صِحَّةِ الصَّلَاةِ الثَّانِيَةِ لِمَنْ يُؤَدِّي فَرِيضَتَهُ خِلَافٌ بَيْنِ الْعُلَمَاءِ. فَمَذْهَبُ أَبِي حَنِيفَةَ وَمَالِكٍ وَأَحْمَد فِي إحْدَى الرِّوَايَتَيْنِ. أَنَّ الْفَرْضَ لَا يَسْقُطُ عَنْ أَهْلِ الْمَسْجِدِ الثَّانِي وَاَللَّهُ أَعْلَمُ. وَسُئِلَ: عَمَّنْ يُصَلِّي الْفَرْضَ خَلْفَ مَنْ يُصَلِّي نَفْلًا؟ . فَأَجَابَ: يَجُوزُ ذَلِكَ فِي أَظْهَرِ قَوْلَيْ الْعُلَمَاءِ وَهُوَ مَذْهَبُ الشَّافِعِيِّ وَأَحْمَد فِي إحْدَى الرِّوَايَتَيْنِ عَنْهُ.