Anas bin Malik reported,

The Prophet ﷺ arrived in Medina when I was nine years old. Umm Sulaym took me to the Prophet of Allah ﷺ and said, "Messenger of Allah, this is my son. Take him into your service."So I served the Prophet ﷺ for nine years. He never said to me about anything I had done, "Why did you do such and such?" Nor did he say to me about anything I had failed to do, "Why didn't you do such and such?"One day he came to me while I was playing with some boys. He greeted us and called me over, then sent me on an errand. When I returned, he said, "Do not tell anyone about it." I had been delayed in returning to my mother, so when I came to her, she asked, "My son, what kept you?"I replied, "The Messenger of Allah ﷺ sent me on an errand."She asked, "What was it?"I said, "He told me not to tell anyone about it."She said, "My son, then keep the secret of the Messenger of Allah ﷺ."

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عن أنس قال

قدم النبي ﷺ المدينة وأنا ابن تسع سنين فانطلقت بي أم سليم إلى نبي الله ﷺ فقالت يا رسول الله هذا ابني استخدمه فخدمت النبي ﷺ تسع سنين فما قال لي لشيء فعلته لم فعلت كذا وكذا وما قال لي لشيء لم أفعله ألا فعلت كذا وكذا وأتاني ذات يوم وأنا ألعب مع الغلمان أو قال مع الصبيان فسلم علينا ودعاني فأرسلني في حاجة فلما رجعت قال لا تخبر أحدا واحتبست على أمي فلما أتيتها قالت يا بني ما حبسك قلت أرسلني رسول الله ﷺ في حاجة له قالت وما هي قلت إنه قال لا تخبر بها أحدا قالت أي بني فاكتم على رسول الله ﷺ سره