Riyad as-Salihin 17:248

Abul-Juhaim 'Abdullah bin Al-Harith (May Allah be pleased with him) said:

The Messenger of Allah (ﷺ) said, "If the person who passes in front of a praying person, realizes the enormity of the sinfulness of this act, it will have been better for him to wait forty than to pass in front of him." [Al-Bukhari and Muslim] . [The narrator was not sure whether the Prophet (ﷺ) said forty days, months or years.]