It was narrated that 'Abdur-Rahman bin Abu laila said:
"Abu Laila used to travel with 'Ali, and he used to wear summer clothes in winter and winter clothes in summer. We said: 'Why don't you ask him (about that)?' He said: "The Messenger of Allah sent for me and my eyes were sore, on the Day of Khaibar. I said: 'O Messenger of Allah, my eyes are sore.' He put some spittle into my eyes, then he said: 'O Allah, take heat and cold away from him.' I never felt hot or cold again after that day. He (the Prophet) said: 'I will send a man who loves Allah and His Messenger, and whom Allah and His Messenger love, and he is not one who flees from the battlefield.' The people craned their necks to see, and he sent for 'Ali and gave it (the banner) to him."

حَدَّثَنَا عُثْمَانُ بْنُ أَبِي شَيْبَةَ، حَدَّثَنَا وَكِيعٌ، حَدَّثَنَا ابْنُ أَبِي لَيْلَى، حَدَّثَنَا الْحَكَمُ، عَنْ عَبْدِ الرَّحْمَنِ بْنِ أَبِي لَيْلَى، قَالَ كَانَ أَبُو لَيْلَى يَسْمُرُ مَعَ عَلِيٍّ فَكَانَ يَلْبَسُ ثِيَابَ الصَّيْفِ فِي الشِّتَاءِ وَثِيَابَ الشِّتَاءِ فِي الصَّيْفِ فَقُلْنَا لَوْ سَأَلْتَهُ فَقَالَ إِنَّ رَسُولَ اللَّهِ ﷺ بَعَثَ إِلَىَّ وَأَنَا أَرْمَدُ الْعَيْنِ يَوْمَ خَيْبَرَ قُلْتُ يَا رَسُولَ اللَّهِ إِنِّي أَرْمَدُ الْعَيْنِ . فَتَفَلَ فِي عَيْنِي ثُمَّ قَالَ " اللَّهُمَّ أَذْهِبْ عَنْهُ الْحَرَّ وَالْبَرْدَ " . قَالَ فَمَا وَجَدْتُ حَرًّا وَلاَ بَرْدًا بَعْدَ يَوْمِئِذٍ . وَقَالَ " لأَبْعَثَنَّ رَجُلاً يُحِبُّ اللَّهَ وَرَسُولَهُ وَيُحِبُّهُ اللَّهُ وَرَسُولُهُ لَيْسَ بِفَرَّارٍ " . فَتَشَوَّفَ لَهَا النَّاسُ فَبَعَثَ إِلَى عَلِيٍّ فَأَعْطَاهَا إِيَّاهُ .