بُلُوغُ الْمَرَامِ
Bulugh al-Maram 239
The Book of Prayer
وَفِي اَلْبُخَارِيِّ : عَنْ عَائِشَةَ - رَضِيَ اَللَّهُ عَنْهَا- أَنَّ ذَلِكَ فِعْلُ اَلْيَهُودِ [1]
And in the narration of al-Bukhari narrated by 'Aishah (RA) is: "This is a practice of the Jews."
Sunnah.com reference: Book 2, Hadith 107