Ruff would not disclose the nature of the injury, which the winger sustained in the third period of Buffalo's 3-2 shootout loss at Boston on Monday.
Hecht wouldn't discuss his injury, but was spotted walking without a limp. He will have additional time to recover during the five-day NHL all-star break that starts Sunday.
He ranks ninth on the team with 25 points - 12 goals and 13 assists - in 43 games, and has been a steady contributor on a line centred by co-captain Daniel Briere, Buffalo's leading scorer.
To replace Hecht, the Sabres recalled rookie forward Drew Stafford from Rochester of the American Hockey League.
Buffalo, which hosts Boston on Wednesday, is suddenly banged up. Forward Paul Gaustad, listed as day to day, missed Monday's game because of an upper body injury and has already been ruled out to play Wednesday.
Defenceman Henrik Tallinder, who's missed six games with a high right ankle sprain, hasn't been cleared to skate and isn't expected back until after the all-star break.