The centre forward was missing from the Bees squad for a 2-1 win over Crystal Palace.
Per The Standard, he is set for a move to Saudi Pro League side Al Ahli for a major fee.
With Toney not present, forwards Yoane Wissa and Bryan Mbeumo scored the goals.
“Various things are going on with Ivan, with transfer rumours and activity. Because of all that full package, we decided to not include him in the squad,” Frank said post-game.
“That was the club and me. That (decision) was made on Thursday. We thought it was the best thing. Ivan is on board, so no problem.
“Like with all good players, one day they will leave the club. Every single time Ivan has not played, Wissa has stepped up.
“Of course, you want your season to start well and you’re pleased when your attacking players are performing. I thought Bryan, Wissa and Kevin (Schade) were a constant threat today.”