Śrīmad-Bhāgavatam · Text 10.24.17
Who is speaking and story frame
देहानुच्चावचाञ्जन्तु: प्राप्योत्सृजति कर्मणा । शत्रुर्मित्रमुदासीन: कर्मैव गुरुरीश्वर: ॥ १७ ॥
dehān uccāvacāñ jantuḥ
prāpyotsṛjati karmaṇā
śatrur mitram udāsīnaḥ
karmaiva gurur īśvaraḥ
Because it is karma that causes the conditioned living entity to accept and then give up different high- and low-grade material bodies, this karma is his enemy, friend and neutral witness, his spiritual master and controlling lord.
Read the purport on Vedabase.ioFrom Canto 10, chapter 14 onward, the translation and purports were completed by Śrīla Prabhupāda's disciples after his departure, and published by the Bhaktivedanta Book Trust.