Hadith: I am Dimām ibn Tha‘labah, from the brothers of Banu Sa‘d ibn Bakr

عن أَنَسَ بْنَ مَالِكٍ رضي الله عنه قال:
بينما نحن جلوس مع النبي صلى الله عليه وسلم في المسجد دخل رجل على جمل، فأناخه في المسجد ثم عقله، ثم قال لهم: أيكم محمد؟ والنبي صلى الله عليه وسلم متكئ بين ظهرانيهم، فقلنا: هذا الرجل الأبيض المتكئ. فقال له الرجل: يا ابن عبد المطلب فقال له النبي صلى الله عليه وسلم: «قد أجبتك». فقال الرجل للنبي صلى الله عليه وسلم: إني سائلك فمشدد عليك في المسألة، فلا تجد علي في نفسك؟ فقال: «سل عما بدا لك» فقال: أسألك بربك ورب من قبلك، آلله أرسلك إلى الناس كلهم؟ فقال: «اللهم نعم». قال: أنشدك بالله، آلله أمرك أن نصلي الصلوات الخمس في اليوم والليلة؟ قال: «اللهم نعم». قال: أنشدك بالله، آلله أمرك أن نصوم هذا الشهر من السنة؟ قال: «اللهم نعم». قال: أنشدك بالله، آلله أمرك أن تأخذ هذه الصدقة من أغنيائنا فتقسمها على فقرائنا؟ فقال النبي صلى الله عليه وسلم: «اللهم نعم». فقال الرجل: آمنت بما جئت به، وأنا رسول من ورائي من قومي، وأنا ضمام بن ثعلبة أخو بني سعد بن بكر.
[صحيح] - [متفق عليه] - [صحيح البخاري: 63]

Anas ibn Mālik (may Allah be pleased with him) reported:
While we were sitting with the Prophet (may Allah’s peace and blessings be upon him) in the mosque, a man came riding on a camel. He made his camel kneel in the mosque, tied its foreleg, and said: "Who amongst you is Muhammad?" At that time, the Prophet (may Allah’s peace and blessings be upon him) was sitting amongst us, leaning on his arm. We replied: "This white man reclining on his arm." The man then addressed him: "O son of ‘Abdul-Muttalib!" The Prophet (may Allah’s peace and blessings be upon him) said: "I am here to answer you." The man said to the Prophet: "I want to ask you something and will be hard in questioning. So do not get angry." The Prophet (may Allah’s peace and blessings be upon him) said: "Ask whatever you want." The man said: "I ask you by your Lord, and the Lord of those who came before you. Has Allah sent you as a messenger to all mankind?" The Prophet (may Allah’s peace and blessings be upon him) replied: "By Allah, yes." The man further said: "I ask you by Allah. Has Allah ordered you to offer five prayers in a day and night?" He replied: "By Allah, yes." The man further said: "I ask you by Allah. Has Allah ordered you to observe fasts during this month of the year?" He replied: "By Allah, yes." The man said: "I ask you by Allah. Has Allah ordered you to take this charity from our rich people and distribute it amongst our poor people?" The Prophet (may Allah’s peace and blessings be upon him) replied: "By Allah, yes." Thereupon, that man said: "I have believed in all that you have been sent with, and I have been sent by my people as a messenger. I am Dimām ibn Tha‘labah, from the brothers of Banu Sa‘d ibn Bakr."
[Authentic hadith] - [Narrated by Bukhari & Muslim] - [Sahih Bukhari - 63]

Explanation

Anas ibn Mālik (may Allah be pleased with him) relates: As the Companions were sitting with the Prophet (may Allah's peace and blessings be upon him) in the mosque, a man riding a camel entered, and he made the camel kneel and tied it. Then, he asked them: Who amongst you is Muhammad? Meanwhile, the Prophet (may Allah's peace and blessings be upon him) was reclining among the people. So, we replied: This white man who is reclining. The man said to him: O son of ‘Abdul-Muttalib! The Prophet (may Allah's peace and blessings be upon him) said to him: I have heard you; ask, and I will answer you. The man said to the Prophet (may Allah's peace and blessings be upon him): I will ask you about something and will be hard in questioning. So do not get upset with me. In other words, do not get angry at me or feel annoyed. He replied: Ask whatever you want. He said: I ask you by your Lord and the Lord of those who came before you. Has Allah sent you as a messenger to mankind? He replied: "By Allah, yes," affirming his truthfulness. The man further said: I ask you by Allah. Has Allah ordered you that we must offer the five prayers in a day and night? They are the obligatory prayers. He replied: By Allah, yes. The man further said: I ask you by Allah. Has Allah ordered you to observe fasts during this month of the year? That's the month of Ramadan. He replied: By Allah, yes. The man said: I ask you by Allah. Has Allah ordered you to take this charity from our rich people and distribute it amongst our poor people?" This is Zakah. The Prophet (may Allah's peace and blessings be upon him) replied: By Allah, yes. Thereupon, Dimām embraced Islam and informed the Prophet (may Allah's peace and blessings be upon him) that he would call his people to Islam, and he introduced himself as Dimām ibn Tha‘labah, from Banu Sa‘d ibn Bakr.