It was narrated from Anas:
"The Messenger of Allah (ﷺ) used to pray 'Asr, then a person could go to Quba'." One of them [1] said: "And he would come to them when they were prayed." The other said: "And the sub was still high."[1] Both Az-Zuhri and Ishaq bin 'Abdullah narrated it from Anas, so the reference is about them.
English reference: Vol. 1, Book 6, Hadith 507
Arabic reference: Book 6, Hadith 510