Sahih al-Bukhari 4721
Prophetic Commentary on the Qur'an (Tafseer of the Prophet (pbuh))
"And they ask you (O Muḥammad ﷺ) concerning the Rūḥ (the Spirit)..." (V.17:85)
Narrated `Abdullah: While I was in the company of the Prophet (ﷺ) on a farm and he was reclining on a palm leave stalk, some Jews passed by. Some of them said to the others. "Ask him (the Prophet (ﷺ) about the spirit." Some of them said, "What urges you to ask him about it" Others said, "(Don't) lest he should give you a reply which you dislike." But they said, "Ask him." So they asked him about the Spirit. The Prophet (ﷺ) kept quiet and did not give them any answer. I knew that he was being divinely inspired so I stayed at my place. When the divine inspiration had been revealed, the Prophet (ﷺ) said. "They ask you (O, Muhammad) concerning the Spirit, Say: "The spirit," its knowledge is with my Lord; and of knowledge you (mankind) have been given only a Little." (17:85)