From Sahih Bukhari (Hadith 6086):
Narrated `Abdullah bin `Umar:When Allah's Apostle was in Ta'if (trying to conquer it), he said to his companions, "Tomorrow we will return (to Medina), if Allah wills." Some of the companions of Allah's Messenger (ﷺ) said, "We will not leave till we conquer it." The Prophet (ﷺ) said, "Therefore, be ready to fight tomorrow." On the following day, they (Muslims) fought fiercely (with the people of Ta'if) and suffered many wounds. Then Allah's Messenger (ﷺ) said, "Tomorrow we will return (to Medina), if Allah wills." His companions kept quiet this time. Allah's Messenger (ﷺ) then smiled
Reference: Bukhari 6086