He sends down the Angels with Spirit from His Command upon whom He wishes of His servants to warn you: "Indeed, there is no deity except Me; so, you heed Me".
In the case of mankind, Spirit is the combination of life and soul 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 18: 109.
It is told in verse 42: 52: “And thus We have revealed to you Spirit from Our command. You did not know what is the Book or belief, but We have made it a Light with which We guide whom We wish of Our servants. And indeed, you are guiding mankind into the Straightpath”. Adhikr-Truth and Proof-revealed to 313 Messengers are to warn mankind that there is no deity except Lord and to serve Him alone as told in verses 21: 24-25. Verse 32: 4 says: “Allah is the one who created the Heaven, the earth and all in between them in six days; then He established on the Throne, you have no protector or intercessor besides Him; will you then remind others in their heart’s language?”. But today, the Arabic Quran reading Fujjar have made their food ‘rejecting Adhikr’. So, whoever holdfast Adhikr, he did holdfast Lord and is guided into the Straightpath as explained in verses 3: 101-102. The word “There is no deity except Allah” is only mentioned verses 37: 35 and 47: 19. See explanation 2: 132, 163 and 16: 102.