Arabic (Original)
أَخْبَرَنَا عَلِيُّ بْنُ مُحَمَّدِ بْنِ عَبْدِ اللهِ بْنِ بِشْرَانَ بِبَغْدَادَ أنبأ إِسْمَاعِيلُ بْنُ مُحَمَّدٍ الصَّفَّارُ ثنا عَبْدُ الْكَرِيمِ بْنُ الْهَيْثَمِ ثنا أَبُو الْيَمَانِ أَخْبَرَنِي شُعَيْبٌ يَعْنِي ابْنَ أَبِي حَمْزَةَ قَالَ قَالَ نَافِعٌ وَكَانَ ابْنُ عُمَرَ إِذَا وَجَدَ الْإِمَامَ قَدْ صَلَّى بَعْضَ الصَّلَاةِ صَلَّى مَعَ الْإِمَامِ مَا أَدْرَكَ إِنْ قَامَ قَامَ وَإِنْ قَعَدَ قَعَدَ حَتَّى يَقْضِيَ الْإِمَامُ صَلَاتَهُ لَا يُخَالِفُهُ فِي شَيْءٍ قَالَ وَكَانَ ابْنُ عُمَرَ ؓ يَقُولُ إِذَا فَاتَتْكَ الرَّكْعَةُ فَقَدْ فَاتَتْكَ السَّجْدَةُ
English Translation
Ali ibn Muhammad ibn Abdullah ibn Bishran informed us in Baghdad, Isma'il ibn Muhammad al-Saffar informed us, Abd al-Karim ibn al-Haytham narrated to us, Abu al-Yaman informed us, Shu'ayb — meaning ibn Abi Hamzah — informed me. He said: Nafi' said: When Ibn Umar found the imam had already prayed part of the prayer, he would pray with the imam whatever he caught — if he stood, he stood; if he sat, he sat — until the imam finished his prayer, not differing from him in anything. Ibn Umar (may Allah be pleased with him) used to say: 'If you miss the rak'ah, you have missed the prostration.'