Musnad Ahmad 187
It was narrated that Jabir bin ‘Abdullah said:
I heard 'Umar bin al-Khattab say to Talhah bin‘Ubaidullah: Why do I see you looking unkempt and dusty since the Messenger of Allah ﷺ died? Perhaps you were upset about your cousin becoming caliph? He said: Allah forbid! I am the most unlikely among you to feel like that, I heard the Messenger of Allah (ﷺ) say: `I know a word which, if a man says it when dying his soul will find rest and provision when it comes out from his body and it will be light for him on the Day of Resurrection.” I did not ask the Messenger of Allah ﷺ about it and he did not tell me it. This is what has been upsetting me. 'Umar said: I know what it is. He said: To Allah be praise! What is it? He said: It is the word that he said to his uncle: La ilaha illallah. Talhah said: You are right.
حَدَّثَنَا عَبْدُ اللَّهِ بْنُ نُمَيْرٍ، عَنْ مُجَالِدٍ، عَنْ عَامِرٍ، عَنْ جَابِرِ بْنِ عَبْدِ اللَّهِ، قَالَ سَمِعْتُ عُمَرَ بْنَ الْخَطَّابِ، رَضِيَ اللَّهُ عَنْهُ يَقُولُ لِطَلْحَةَ بْنِ عُبَيْدِ اللَّهِ مَا لِي أَرَاكَ قَدْ شَعِثْتَ وَاغْبَرَرْتَ مُنْذُ تُوُفِّيَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ لَعَلَّكَ سَاءَكَ يَا طَلْحَةُ إِمَارَةُ ابْنِ عَمِّكَ قَالَ مَعَاذَ اللَّهِ إِنِّي لَأَجْدَرُكُمْ أَنْ لَا أَفْعَلَ ذَلِكَ إِنِّي سَمِعْتُ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ يَقُولُ إِنِّي لَأَعْلَمُ كَلِمَةً لَا يَقُولُهَا أَحَدٌ عِنْدَ حَضْرَةِ الْمَوْتِ إِلَّا وَجَدَ رُوحَهُ لَهَا رَوْحًا حِينَ تَخْرُجُ مِنْ جَسَدِهِ وَكَانَتْ لَهُ نُورًا يَوْمَ الْقِيَامَةِ فَلَمْ أَسْأَلْ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ عَنْهَا وَلَمْ يُخْبِرْنِي بِهَا فَذَلِكَ الَّذِي دَخَلَنِي قَالَ عُمَرُ رَضِيَ اللَّهُ عَنْهُ فَأَنَا أَعْلَمُهَا قَالَ فَلِلَّهِ الْحَمْدُ فَمَا هِيَ قَالَ هِيَ الْكَلِمَةُ الَّتِي قَالَهَا لِعَمِّهِ لَا إِلَهَ إِلَّا اللَّهُ قَالَ طَلْحَةُ صَدَقْتَ‏.‏