‘that they will take,’ meaning the believers will take them until the Day of Resurrection.
‘The matter descends,’ meaning: the revelation ‘between them,’ between the heaven and the earth. ‘That you may know,’ by this revelation, ‘that Allah is powerful over all things and that Allah has encompassed all things in knowledge,’ nothing escapes His knowledge.
Muhammad said: ‘Knowledge’ is accusative as a corroborative infinitive (al-masdar al-mu'akkid). The meaning is: He has known everything with knowledge. This part concludes with the praise of Allah.