صحيح ابن خزيمه
Sahih Ibn Khuzaymah
جماع أبواب صلاة الخوفChapters on Fear Prayer
(624) بَابٌ فِي صِفَةِ الْخَوْفِ أَيْضًا وَالْخَوْفُ أَشَدُّ مِمَّا تَقَدَّمَ ذِكْرُنَا لَهُ فِي الْبَابِ قَبْلَ هَذَا،624| Another description of the fear prayer, with greater danger than previously mentioned
Hadith Q1351
وَإِبَاحَةِ افْتِتَاحِ الصَّفِّ الثَّانِي صَلَوَاتِهِمْ مَعَ الْإِمَامِ وَهُمْ قُعُودٌ وَافْتِتَاحِ الصَّفِّ الْأَوَّلِ صَلَوَاتِهِمْ مَعَ الْإِمَامِ وَهُمْ قِيَامٌ
It is permissible to start the prayer while sitting with the imam in the second row, and it is permissible for those in the first row to start the prayer while standing with the imam.
