Why did Prophet Muhammad perform stoning if it was not advised through quran?

As per following Hadith, Muhammad (sa) ordered and performed stoning as punishment for adultery. It was even performed to a woman. > Sahih Muslim (17:4196) - A married man confesses to adultery. > Muhammad orders him planted in the ground and pelted with stones. > According to the passage, the first several stones caused such pain > that he tried to escape and had to be dragged back. . > Sahih Muslim (17:4206) - A woman who became pregnant confesses to > Muhammad that she is guilty of adultery. Muhammad allows her to have > the child, then has her stoned. The description is graphic: "Khalid b > Walid came forward with a stone which he flung at her head and there > spurted blood on the face of Khalid and so he abused her." According to following Quran verses, punishment for adultery is 100 lashes or house arrest maximum. > an-Nur, 24:2 The adulteress and adulterer should be flogged a hundred lashes each, > and no pity for them should deter you from the law of God, if you > believe in God and the Last Day; and the punishment should be > witnessed by a body of believers. . > an-Nisa', 4:15 If any of your women is guilty of unnatural offence, > bring four of your witnesses to give evidence; if they testify against > them, retain them in the houses until death overtakes them or God > provides some other way for them. So, if stoning was not advised in quran, how come Muhammad (sa) made such decisions?