And they ask you about the Spirit (Rooh). You say: "The Spirit belongs to the Command of my Lord; and mankind has not been given of knowledge except a little".
The Knowledge Adhikr was not codified during the revelation of this verse. But today, Adhikr-the Best Interpretation of Lord’s Book mentioned in verse 25: 33- which explains everything is codified. So whoever even the Messenger should ask about the Impartial Lord to the author of Ahikr as explained in verse 16: 43.
Spirit is the combination of life and soul in the case of creatures as mentioned in verse 32: 9. Angel Jibreel is mentioned as the Spirit in verse 26: 93 and 78: 38. Adhikr is denoted as Spirit, i.e. the Words of Lord as told in verse 42: 52. See explanation 16: 1-2 and 17: 55.