He used to pray Maghrib with the Prophet ﷺ when the sun had disappeared behind the veil of the horizon.
حدثنا يعقوب بن حميد بن كاسب حدثنا المغيرة بن عبد الرحمن عن يزيد بن أبي عبيد
أنه كان يصلي مع النبي ﷺ المغرب إذا توارت بالحجاب
No references are available.
Bukhari narrated it in "Prayer Times," chapter "The Time of Maghrib," no. 561, and Muslim in "Mosques," chapter "Explaining that the beginning of the time of Maghrib is..." no. 636, from the hadith of Yazid, with this wording.