Abu Musa Ashari reported,

The Prophet ﷺ entered a garden and instructed me to guard its gate. A man came seeking permission to enter, and the Prophet ﷺ said, "Let him in, and give him the glad tidings of Paradise." It was Abu Bakr.Then another came seeking permission, and he said, "Let him in, and give him the glad tidings of Paradise." It was Umar.Then another came seeking permission. The Prophet ﷺ paused for a moment, then said, "Let him in, and give him the glad tidings of Paradise, along with a trial that will befall him." It was Uthman bin Affan.Hammad said, Asim Ahwal and Ali bin Hakam also narrated to us, both having heard Abu Uthman relate from Abu Musa something similar. Asim added in his version that the Prophet ﷺ was sitting in a place where there was water, with his knees, or one of his knees, uncovered. When Uthman entered, he covered them.

Bukhari 3695

Sahih

حدثنا سليمان بن حرب حدثنا حماد بن زيد عن أيوب عن أبي عثمان

عن أبي موسى رضي الله عنه

أن النبي ﷺ دخل حائطا وأمرني بحفظ باب الحائط فجاء رجل يستأذن فقال ائذن له وبشره بالجنة فإذا أبو بكر ثم جاء آخر يستأذن فقال ائذن له وبشره بالجنة فإذا عمر ثم جاء آخر يستأذن فسكت هنيهة ثم قال ائذن له وبشره بالجنة على بلوى ستصيبه فإذا عثمان بن عفان قال حماد وحدثنا عاصم الأحول وعلي بن الحكم سمعا أبا عثمان يحدث عن أبي موسى بنحوه وزاد فيه عاصم أن النبي ﷺ كان قاعدا في مكان فيه ماء قد انكشف عن ركبتيه أو ركبته فلما دخل عثمان غطاها

البخاري 3695صحيح
Contents
Reference
Commentary
Ayat
Collection
Sahih Bukhari
Book
Virtues of the companions of the Prophet ﷺ
Chapter
Virtues of Uthman bin Affan Abu Amr Qurashi, may Allah be pleased with him
Numbering
Darussalam 3695
Bukhari 3695