It wasnarrated from Busr bin Sa'eed that Zaid bin Khalid sent wordto AbuJuhaim Al-Ansari asking him:
"What did you hear from theProphet(ﷺ) about a man when he is performing prayer?" He said: "Iheard the Prophet (ﷺ) saying: 'If anyone of you knew (how greatisthe sin involved) when he passed in front of his brother who isperforming prayer, then waiting for forty'," (one of thenarrators)said: "I do not know if he meant forty years, fortymonths, or fortydays, 'would be better for him than that."
English reference: Vol. 1, Book 5, Hadith 945
Arabic reference: Book 5, Hadith 998