Praise be to Allah.
We put this question to Shaykh Muhammad ibn Saalih al-‘Uthaymeen, may Allaah preserve him, who answered as follows:
If he knows that they want that to help them engage in this haraam transaction, then it is haraam, because the Prophet SAWS (peace and blessings of Allaah be upon him) cursed the one who consumes ribaa, the one who gives it, the two who witness it and the one who records it. And Allaah has forbidden this when He said (interpretation of the meaning):
“… do not help one another in sin and transgression…” [al-Maa’idah 5:2]
And Allaah knows best.