Sunan an-Nasa'i, Volume 5, Book 37, Hadith 4084 (DarusSalam) ⓘ

It was narrated that Abu Hurairah said: "The Messenger of Allah [SAW] said: 'Whoever ties a know and blows on it, he has practiced magic; and whoever practices magic, he has committed Shirk; and whoever hangs up something (as an amulet) will be entrusted to it.'"

أَخْبَرَنَا عَمْرُو بْنُ عَلِيٍّ، قَالَ حَدَّثَنَا أَبُو دَاوُدَ، قَالَ حَدَّثَنَا عَبَّادُ بْنُ مَيْسَرَةَ الْمِنْقَرِيُّ، عَنِ الْحَسَنِ، عَنْ أَبِي هُرَيْرَةَ، قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏ "‏ مَنْ عَقَدَ عُقْدَةً ثُمَّ نَفَثَ فِيهَا فَقَدْ سَحَرَ وَمَنْ سَحَرَ فَقَدْ أَشْرَكَ وَمَنْ تَعَلَّقَ شَيْئًا وُكِّلَ إِلَيْهِ ‏" ‏ ‏.‏