Yahya related to me that Malik said, "I have heard from Nafi that Abdullah ibn Umar used to see his son, Ubaydullah ibn Abdullah, doing voluntary prayers on a journey,and he would not disapprove of it
Gradings in the source
Mauquf DaifSalim al-Hilali
Under each narration is the dataset’s own translation, shown as it stands. It names no translator, its rights are not verified, and nobody has checked it against the Arabic; some narrations have none. The Arabic is the text.
The Arabic text, the numbering, the book names and the gradings are shown exactly as they stand in an open dataset (hadith-api). Sabīl has not yet verified its accuracy or its rights, and its scholarly review has not begun. Until then, check a narration against a printed edition before relying on it.