Usama reported,

A daughter of the Messenger of Allah ﷺ sent word to him while Usama bin Zayd, Saad, and Ubayy were with the Messenger of Allah ﷺ, saying, "My son is dying, so come and be with us."He sent back his greetings of peace and said, "To Allah belongs what He takes and what He gives, and everything with Him has an appointed term. So let her be patient and seek her reward."She sent word to him again, urging him by oath to come. So he stood, and we stood with him. When he sat down, the child was lifted to him and placed in his lap, the boy's breath rattling. The eyes of the Messenger of Allah ﷺ overflowed with tears.Saad asked, "What is this, Messenger of Allah?"He replied, "This is mercy that Allah has placed in the hearts of whichever of His servants He wills. Allah shows mercy only to those of His servants who are merciful."

Bukhari 6655

Sahih

حدثنا حفص بن عمر حدثنا شعبة أخبرنا عاصم الأحول سمعت أبا عثمان يحدث

عن أسامة

أن بنتا لرسول الله ﷺ أرسلت إليه ومع رسول الله ﷺ أسامة بن زيد وسعد وأبي أن ابني قد احتضر فاشهدنا فأرسل يقرأ السلام ويقول إن لله ما أخذ وما أعطى وكل شيء عنده مسمى فلتصبر وتحتسب فأرسلت إليه تقسم عليه فقام وقمنا معه فلما قعد رفع إليه فأقعده في حجره ونفس الصبي جئث ففاضت عينا رسول الله ﷺ فقال سعد ما هذا يا رسول الله قال هذه رحمة يضعها الله في قلوب من يشاء من عباده وإنما يرحم الله من عباده الرحماء

البخاري 6655صحيح
Contents
Reference
Commentary
Ayat
Collection
Sahih Bukhari
Book
Oaths and vows
Chapter
Saying of Allah the Exalted, "And they swore by Allah their strongest oaths"
Numbering
Darussalam 6655
Bukhari 6655