Ben Ish Hai · Halachot 2nd Year, Pekudei, Chapter 11
1
הרוקק ברוח והרוח מפזר הרוק – אסור, משום דדמי לזורה; ואע"ג דאין מתכון לכך - פסיק רישא הוא ואסור מדרבנן. ואע"ג דיש חולקים על זה - רבו האחרונים ז"ל דחיישי לזה.
One who spits into the wind, and the wind scatters the spit, it is forbidden, on account of its similarity to winnowing; even though there is no intention to do it- being unavoidable [that it will be winnowed], it is forbidden by the Rabbanan. And even though there are those who disagree with this, many Acharonim, blessed be their memory, are concerned with this.
הרוקק ברוח והרוח מפזר הרוק – אסור, משום דדמי לזורה; ואע"ג דאין מתכון לכך - פסיק רישא הוא ואסור מדרבנן. ואע"ג דיש חולקים על זה - רבו האחרונים ז"ל דחיישי לזה.
One who spits into the wind, and the wind scatters the spit, it is forbidden, on account of its similarity to winnowing; even though there is no intention to do it- being unavoidable [that it will be winnowed], it is forbidden by the Rabbanan. And even though there are those who disagree with this, many Acharonim, blessed be their memory, are concerned with this.