﴿ تَنَزَّلُ ٱلْمَلَٰٓئِكَةُ وَٱلرُّوحُ فِيهَا بِإِذْنِ رَبِّهِم مِّن كُلِّ أَمْرٍۢ ﴾

“in hosts descend in it the angels, bearing divine inspiration by their Sustainer's leave; from all [evil] that may happen”

The angels and the Spirit namely Gabriel descend tanazzalu one of the two original tā’ letters of tatanazzalu has been omitted in it on that night by the leave of their Lord by His command with every command that God has decreed from that year to the following one min is causative functioning as bi ‘with’.