Abdullah bin Abbas reported,

When news of the Prophet's ﷺ mission reached Abu Dharr, he said to his brother, "Ride out to this valley and bring me information about this man who claims to be a prophet receiving news from heaven. Listen to what he says, then come back to me."The brother set out, met him, listened to his words, then returned to Abu Dharr and told him, "I saw him commanding noble character, and his speech is not poetry."Abu Dharr said, "You have not satisfied what I sought."So he took provisions and carried a waterskin filled with water until he arrived in Mecca. He went to the sacred mosque and looked for the Prophet ﷺ, though he did not recognize him, and he was reluctant to ask about him. When part of the night had passed, he lay down. Ali saw him and recognized that he was a stranger, so when he saw him, he had him follow along. Neither of them asked the other about anything until morning came. Then Abu Dharr carried his waterskin and his provisions back to the mosque and spent that day there without seeing the Prophet ﷺ, until evening came, when he returned to his sleeping place.Ali passed by him and said, "Has the time not come for the man to know his lodging?" He had him get up and took him along with him, neither of them asking the other about anything. When it was the third day, Ali did the same, and Abu Dharr stayed with him.Then Ali said, "Will you not tell me what brought you here?"Abu Dharr replied, "If you give me a pledge and a covenant that you will guide me rightly, I will."Ali did so, and Abu Dharr informed him.Ali said, "It is the truth, and he is the Messenger of Allah ﷺ. When morning comes, follow me. If I see something I fear for you, I will stand as though pouring out water. If I continue on, follow me until you enter where I enter."He did so, and Abu Dharr walked behind him until Ali entered upon the Prophet ﷺ, and Abu Dharr entered with him. He listened to his words and accepted Islam on the spot.The Prophet ﷺ said to him, "Return to your people and inform them, until my command reaches you."Abu Dharr said, "By the One in whose hand my soul is, I will proclaim it aloud among them."He went out until he came to the sacred mosque and called out at the top of his voice, "I bear witness that there is no god but Allah and that Muhammad is the Messenger of Allah."The people then rose and beat him until they knocked him to the ground. Abbas came and threw himself over him, saying, "Woe to you! Do you not know that he is from Ghifar, and that the route of your traders to Syria passes through them?" Thus he rescued him from them.The next day Abu Dharr returned and did the same, and they beat him and rushed at him, and Abbas threw himself over him.

حدثني عمرو بن عباس حدثنا عبد الرحمن بن مهدي حدثنا المثنى عن أبي جمرة

عن ابن عباس رضي الله عنهما قال

لما بلغ أبا ذر مبعث النبي ﷺ قال لأخيه اركب إلى هذا الوادي فاعلم لي علم هذا الرجل الذي يزعم أنه نبي يأتيه الخبر من السماء واسمع من قوله ثم ائتني فانطلق الأخ حتى قدمه وسمع من قوله ثم رجع إلى أبي ذر فقال له رأيته يأمر بمكارم الأخلاق وكلاما ما هو بالشعر فقال ما شفيتني مما أردت فتزود وحمل شنة له فيها ماء حتى قدم مكة فأتى المسجد فالتمس النبي ﷺ ولا يعرفه وكره أن يسأل عنه حتى أدركه بعض الليل فاضطجع فرآه علي فعرف أنه غريب فلما رآه تبعه فلم يسأل واحد منهما صاحبه عن شيء حتى أصبح ثم احتمل قربته وزاده إلى المسجد وظل ذلك اليوم ولا يراه النبي ﷺ حتى أمسى فعاد إلى مضجعه فمر به علي فقال أما نال للرجل أن يعلم منزله فأقامه فذهب به معه لا يسأل واحد منهما صاحبه عن شيء حتى إذا كان يوم الثالث فعاد علي على مثل ذلك فأقام معه ثم قال ألا تحدثني ما الذي أقدمك قال إن أعطيتني عهدا وميثاقا لترشدني فعلت ففعل فأخبره قال فإنه حق وهو رسول الله ﷺ فإذا أصبحت فاتبعني فإني إن رأيت شيئا أخاف عليك قمت كأني أريق الماء فإن مضيت فاتبعني حتى تدخل مدخلي ففعل فانطلق يقفوه حتى دخل على النبي ﷺ ودخل معه فسمع من قوله وأسلم مكانه فقال له النبي ﷺ ارجع إلى قومك فأخبرهم حتى يأتيك أمري قال والذي نفسي بيده لأصرخن بها بين ظهرانيهم فخرج حتى أتى المسجد فنادى بأعلى صوته أشهد أن لا إله إلا الله وأن محمدا رسول الله ثم قام القوم فضربوه حتى أضجعوه وأتى العباس فأكب عليه قال ويلكم ألستم تعلمون أنه من غفار وأن طريق تجاركم إلى الشأم فأنقذه منهم ثم عاد من الغد لمثلها فضربوه وثاروا إليه فأكب العباس عليه