Sahl reported,

On the day of Khaybar, the Prophet ﷺ said, "Tomorrow I shall give the banner to a man at whose hands Allah will grant victory, a man who loves Allah and His Messenger and whom Allah and His Messenger love."The people spent the night wondering which of them would be given it, and in the morning they all came eagerly hoping for it.The Prophet ﷺ asked, "Where is Ali?"He was told, "He is suffering from a complaint in his eyes."So he spat into his eyes and prayed for him, and Ali was healed as though he had never had any pain. The Prophet ﷺ then handed him the banner.Ali asked, "Shall I fight them until they become like us?"He replied, "Advance calmly until you reach their territory, then call them to Islam and inform them of what is required of them. By Allah, for Allah to guide a single man through you is better for you than red camels."

Bukhari 3009

Sahih

حدثنا قتيبة بن سعيد حدثنا يعقوب بن عبد الرحمن بن محمد بن عبد الله بن عبد القاري عن أبي حازم قال أخبرني

سهل رضي الله عنه يعني ابن سعد قال

قال النبي ﷺ يوم خيبر لأعطين الراية غدا رجلا يفتح على يديه يحب الله ورسوله ويحبه الله ورسوله فبات الناس ليلتهم أيهم يعطى فغدوا كلهم يرجوه فقال أين علي فقيل يشتكي عينيه فبصق في عينيه ودعا له فبرأ كأن لم يكن به وجع فأعطاه فقال أقاتلهم حتى يكونوا مثلنا فقال انفذ على رسلك حتى تنزل بساحتهم ثم ادعهم إلى الإسلام وأخبرهم بما يجب عليهم فوالله لأن يهدي الله بك رجلا خير لك من أن يكون لك حمر النعم

البخاري 3009صحيح
Contents
Reference
Commentary
Ayat
Collection
Sahih Bukhari
Book
Jihad and expeditions
Chapter
Virtue of one at whose hands a man accepted Islam
Numbering
Darussalam 3009
Bukhari 3009