Rennes president Olivier Létang has hinted Watford met their €40m price for Ismaila Sarr.
Watford landed Sarr for a mooted record sale for Rennes.
Letang told RMC: "I have had a coherent speech for some time. I said that if the price was reached, Sarr could leave.
"This was not the case this morning (yesterday). From the moment when Watford met our expectations and the price set, it was necessary to respect our word in relation to the player.
"We wish him the best. 38 million euros (for the transfer)? You are not very far."