大乘百法明門論開宗義決 1.40

1.40

然此五乘有開合者。或有聖教於三乘外開人天乘。五戒十善因果別故。合不定性入三乘中。隨所得果皆出世故。或有聖教人天合一。五戒十善世間法故。於三乘外開不定性。雖同出世種性異故。

Regarding "yet these five vehicles have divisions and combinations": Some sacred teachings, outside the three vehicles, open up the human and deva vehicles, because the causes and effects of the five precepts and ten virtuous deeds are distinct; and they combine the indeterminate nature into the three vehicles, because whatever fruit they attain is transworldly. Other sacred teachings combine humans and devas into one, because the five precepts and ten virtuous deeds are worldly dharmas; and outside the three vehicles they open up the indeterminate nature, because although they are equally transworldly, their spiritual lineages are different.