Abu Dawud said: According to some (scholars), there is a narrator between the narrator Khalid and Abu Qilabah.
In-book : Book 32, Hadith 28
English translation : Book 31, Hadith 3985
32. 'Dialects and Readings of the Qur''an (Kitab Al-Huruf Wa Al-Qira''at)'
باب التَّخَلِّي عِنْدَ قَضَاءِ الْحَاجَةِ