Zayd bin Khalid al-Juhani sent him to Abu Juhaym to ask what he had heard from the Messenger of Allah ﷺ regarding a person who passes in front of someone praying, and what the consequence is for doing so.Abu Juhaym said, "The Messenger of Allah ﷺ said, 'If the one who passes in front of a person praying knew what was upon him, standing still for forty would be better for him than passing in front of him.'"Abu Nadr said, "I do not know whether he said forty days, forty months, or forty years."
قال قرأت على عبد الرحمن: مالك عن أبي النضر مولى عمر بن عبيد الله
أن زيد بن خالد الجهني أرسله إلى أبي جهيم يسأله ماذا سمع من رسول الله ﷺ في المار بين يدي المصلي ماذا عليه قال أبو الجهيم قال رسول الله ﷺ لو يعلم المار بين يدي المصلي ماذا عليه لكان أن يقف أربعين خيرا له من أن يمر بين يديه قال أبو النضر لا أدري أقال أربعين يوما أو أربعين شهرا أو أربعين سنة
Its isnad is sahih. Abu Nadr is Salim bin Abu Umaya, the freedman of Umar bin Ubaydullah al-Madani, a trustworthy, firmly reliable, and well-known narrator among the junior successors. Busr bin Saeed al-Madani is among the eminent trustworthy successors. Zayd bin Khalid Juhani is a companion we have encountered before, and he has several hadiths. This hadith has come up many times before, and it is found in Bukhari 1/584, no. 510 (Fath), Muslim 1/363, no. 507, Abu Dawud 1/187, no. 701, Tirmidhi 1/159, no. 336, and Nasai 2/66, no. 756.