Blowing as a necromancer when making incantations.
(1) it occurs in this sense in the Qur’am, Surah cxiii. 4: “I seek refuge…. from the evil of the blowers upon knots.” Referring to those witches who make knots in a string and blow upon them, uttering some incantation.
(2) It is also used for the inspirations which Muhammad professed to have received from Gabriel. (Majma’u ‘l-Bihar, p. 376.)
Based on Hughes, Dictionary of Islam