瑜伽論記 7.525

7.525

彼諸有情與己平等者，此明於自他身平等與樂，文中但云與己平等與己相似當與彼樂，將知平等亦與己樂，自他俱與，名於內外修循身觀。泰云：如我既欲樂背苦，彼諸有情亦復如是欲樂背苦，我當與彼利益安樂，名內外觀。

Regarding "those sentient beings are equal to oneself": this clarifies bestowing happiness equally upon one's own and others' bodies. The text merely says "equal to oneself, similar to oneself, one should bestow happiness upon them"; from this one knows that being equal also means bestowing happiness upon oneself. Bestowing it upon both oneself and others is called cultivating the contemplation of the body observing the body internally and externally. Tai says: just as I desire happiness and turn away from suffering, those sentient beings likewise desire happiness and turn away from suffering; I should bestow benefit, peace, and happiness upon them. This is called internal and external contemplation.