Quotes from Sūtra on Upāsaka Precepts,
Vol. 1, Chapter 1
On the Assembly
“Good son, no sentient being has the bodhi nature [in the first place] or the [definite] nature of a human, heavenly being, lion, tiger, wolf, dog, and so forth. In one’s present life, one becomes a human or heavenly being based on the causes and conditions of various good karmas one has ever accumulated. It is also through the causes and conditions of the bad karmas one has accumulated that in one’s present life that one is born an animal, such as a lion. The same is true for a bodhisattva. It is through the combination of various good karmas and the arousal of the aspiration for Bodhicitta that one comes to be called a bodhisattva.”
優婆塞戒經 卷一
〈集會品〉第一
【善男子！一切眾生無菩提性，如諸眾生無人天性、師子虎狼狗犬等性。現在世中和合眾善業因緣故，得人天身；和合不善業因緣故，得師子等畜生之身；菩薩亦爾，和合眾善業因緣故發菩提心，故名菩薩。】