大乘起信論義記 3.230

3.230

又為凡夫所見者，是其麁色，隨於六道各見不同，種種異類非受樂相故，說為應身。

'Furthermore, that which is seen by ordinary beings is its coarse form. According to the six destinies, what each sees is different; these manifold diverse types are not marks of experiencing bliss, and therefore it is called the response body (nirmāṇakāya).'