An al-Qaeda-linked group in Syria says a nearly week-old cease-fire brokered by Russia and Turkey is “humiliating” and that those who agreed to it made a “big mistake.” The cease-fire, which excludes the al-Qaeda-linked Fatah al-Sham Front as well as the Islamic State group, has largely held, except for intense fighting in the Barada Valley outside Damascus, a major source of water for the capital.