Anas bin Malik said:

"while we were with the Messenger of Allah, sitting in the Masjid, a man entered on a camel. He made it kneel in the Masjid, then he hobbled it. Then he said; 'Which of you is Muhammad?' He was reclining among them, and we said to him: 'This white man who is reclining.' The man said to him: 'O son of 'Abdul-Muttalib.' The Messenger of Allah said to him: 'I have answered you.' The man said: 'O Muhammad, I am going to ask you questions and I will be harsh in asking.' He said; 'Ask whatever you like.' The man said; 'I adjure you by your Lord, and the Lord of those who came begfore you, has Allah sent you to all the people?' The messenger of Allah said: 'by Allah, yes,' He said: 'Iadjure you by Allah, has Allah commanded you to fast this month each year?' The Messenger of Allah said: 'I adjure you by Allah, has Allah commanded you to take this charity from our rich and divide it among our poor?' The Messenger of Allah said: 'By Allah, Yes.' The ma said; 'I believe in that which you have brought, and I am the envoy of my people who are coming after me. I am Dimam bin Thalabah, the brother of Banu sad bin Bakr."' 'Ubaidullah bin 'Umar contradicted him.

أَخْبَرَنَا عُبَيْدُ اللَّهِ بْنُ سَعْدِ بْنِ إِبْرَاهِيمَ، مِنْ كِتَابِهِ قَالَ حَدَّثَنَا عَمِّي، قَالَ حَدَّثَنَا اللَّيْثُ، قَالَ حَدَّثَنَا ابْنُ عَجْلاَنَ، وَغَيْرُهُ، مِنْ إِخْوَانِنَا عَنْ سَعِيدٍ الْمَقْبُرِيِّ، عَنْ شَرِيكِ بْنِ عَبْدِ اللَّهِ بْنِ أَبِي نَمِرٍ، أَنَّهُ سَمِعَ أَنَسَ بْنَ مَالِكٍ، يَقُولُ بَيْنَمَا نَحْنُ عِنْدَ رَسُولِ اللَّهِ ﷺ جُلُوسٌ فِي الْمَسْجِدِ دَخَلَ رَجُلٌ عَلَى جَمَلٍ فَأَنَاخَهُ فِي الْمَسْجِدِ ثُمَّ عَقَلَهُ ثُمَّ قَالَ أَيُّكُمْ مُحَمَّدٌ - وَهُوَ مُتَّكِئٌ بَيْنَ ظَهْرَانَيْهِمْ - فَقُلْنَا لَهُ هَذَا الرَّجُلُ الأَبْيَضُ الْمُتَّكِئُ فَقَالَ لَهُ الرَّجُلُ يَا ابْنَ عَبْدِ الْمُطَّلِبِ . فَقَالَ لَهُ رَسُولُ اللَّهِ ﷺ " قَدْ أَجَبْتُكَ " . قَالَ الرَّجُلُ يَا مُحَمَّدُ إِنِّي سَائِلُكَ فَمُشَدِّدٌ عَلَيْكَ فِي الْمَسْأَلَةِ . قَالَ " سَلْ عَمَّا بَدَا لَكَ " . قَالَ أَنْشُدُكَ بِرَبِّكَ وَرَبِّ مَنْ قَبْلَكَ آللَّهُ أَرْسَلَكَ إِلَى النَّاسِ كُلِّهِمْ فَقَالَ رَسُولُ اللَّهِ ﷺ " اللَّهُمَّ نَعَمْ " . قَالَ فَأَنْشُدُكَ اللَّهَ آللَّهُ أَمَرَكَ أَنْ تَصُومَ هَذَا الشَّهْرَ مِنَ السَّنَةِ قَالَ قَالَ رَسُولُ اللَّهِ ﷺ " اللَّهُمَّ نَعَمْ " . قَالَ فَأَنْشُدُكَ اللَّهَ آللَّهُ أَمَرَكَ أَنْ تَأْخُذَ هَذِهِ الصَّدَقَةَ مِنْ أَغْنِيَائِنَا فَتَقْسِمَهَا عَلَى فُقَرَائِنَا فَقَالَ رَسُولُ اللَّهِ ﷺ " اللَّهُمَّ نَعَمْ " . فَقَالَ الرَّجُلُ إِنِّي آمَنْتُ بِمَا جِئْتَ بِهِ وَأَنَا رَسُولُ مَنْ وَرَائِي مِنْ قَوْمِي وَأَنَا ضِمَامُ بْنُ ثَعْلَبَةَ أَخُو بَنِي سَعْدِ بْنِ بَكْرٍ . خَالَفَهُ عُبَيْدُ اللَّهِ بْنُ عُمَرَ .