The Egyptian giants on Monday announced that they had amicably parted ways with Mosimane after a two-year spell.
De Sa, who was working as an assistant to Carlos Queiroz with the Egyptian national team made interesting comments regarding Mosimane's future.
"Pitso is going to Qatar," De Sa revealed to KickOff.
"It's a different league, it's a different set-up, but the money will be better.
"His relationship with the Egyptians was a love-hate relationship at times.
"Pitso is outspoken as we all know, and he will always speak his mind.
"So he had that scenario, but he did well. I mean, he kept taking the team to the Champions League final.
"With the most recent final, the fact that it was played in Morocco was probably the reason why he didn't win it.
"I think he did an excellent job. I attended many Al Ahly matches, and the supporters were quite good to him.
"I know some Egyptian reporters were quite negative towards him at times, but you'll always have some controversy."
Mosimane's representatives recently dismissed speculation linking him to a lucrative move to Qatar.
"I did speak to him a few times, and he did mention to me that there was an offer from Qatar that he was considering," De Sa added.
"I think once he lost the final, that was played in Morocco I think that was the straw that broke the camel's back. It was time to go.
"It's not confirmed yet, it's speculation from my side but that's what I think."