Abdul-Rahman bin Abu Layla reported,

Abu Layla used to spend evenings in conversation with Ali, and he would wear summer clothes in winter and winter clothes in summer. We said, "We should ask him about this."So he asked him, and Ali said, "The Messenger of Allah ﷺ sent for me on the day of Khaybar while I was suffering from sore eyes."I said, "Messenger of Allah, my eyes are sore."He spat into my eyes and said, "O Allah, remove from him the heat and the cold."Ali said, "I have not felt heat or cold since that day."He also said, "I will surely send a man who loves Allah and His Messenger and whom Allah and His Messenger love, one who does not flee from battle."The people craned their necks hoping to be the one chosen, but he sent for Ali and gave the banner to him.

حدثنا عثمان بن أبي شيبة حدثنا وكيع حدثنا ابن أبي ليلى حدثنا الحكم

عن عبد الرحمن بن أبي ليلى قال

كان أبو ليلى يسمر مع علي فكان يلبس ثياب الصيف في الشتاء وثياب الشتاء في الصيف فقلنا لو سألته فقال إن رسول الله ﷺ بعث إلي وأنا أرمد العين يوم خيبر قلت يا رسول الله إني أرمد العين فتفل في عيني ثم قال اللهم أذهب عنه الحر والبرد قال فما وجدت حرا ولا بردا بعد يومئذ وقال لأبعثن رجلا يحب الله ورسوله ويحبه الله ورسوله ليس بفرار فتشرف له الناس فبعث إلى علي فأعطاها إياه