"Indeed, I have rewarded them this Day for their patience" in the worldly life. "Indeed, it is they"—meaning that they—"who are the successful," the ones saved from the Fire. It is also recited with a kasra: "inna-hum" (indeed, they).
Muhammad said: As for the one who recites with the kasra, the meaning is: I have rewarded them for their patience, then He informs [us] by saying: Indeed, they are the successful ones.