Abdullah bin Yasar relates that Amr bin Hurayth visited Sayyiduna al-Hasan bin Ali (may Allah be pleased with them both) in his illness, and Sayyiduna Ali (may Allah be pleased with him) asked him: "Are you visiting al-Hasan while there is in your heart (towards us) all that (rancour and hostility) which is there?" To this Amr replied to him: "You are not my Lord, that you can turn my heart wherever you wish." Sayyiduna Ali (may Allah be pleased with him) said: "In any case, that does not prevent us from giving you sincere counsel. I heard the Messenger of Allah (peace and blessings be upon him) say: 'There is no Muslim who visits a (Muslim) brother of his except that Allah Almighty sends out seventy thousand angels for him' (the full hadith)."
Imam Ahmad bin Mani' recorded it from Yazid, and Imam al-Harith from Affan, both through Hammad bin Salamah.
Hadith Referenceالمطالب العالية بزوائد المسانيد الثمانية / كتاب الطب / 2469
Hadith Takhrij«حکم الحدیث المطالب العالیہ محققاً تنسیق د. سعد بن ناصر بن عبد العزيز الشَّثري- مکتبہ شاملہ :—. » «أخرجه سنن الترمذي برقم: 969، وأخرجه سنن أبي داود برقم: 3098، وأخرجه سنن ابن ماجه برقم: 1442، وأخرجه مسند أحمد برقم: 756، وأخرجه مسند البزار برقم: 620، 777، وأخرجه المستدرك على الصحيحين برقم: 1304، وأخرجه المعجم الأوسط للطبراني برقم: 1322، 7460، وأخرجه صحيح ابن حبان برقم: 2958»