Bhagavad Gita 8.23

Now, I will tell you, O Arjuna, the times at which, if the mystics go forth, they do not return, and at which they go forth only to return.

यत्र काले त्वनावृत्तिमावृत्तिं चैव योगिनः।
प्रयाता यान्ति तं कालं वक्ष्यामि भरतर्षभ॥

yatra kāle tvanāvṛttimāvṛttiṃ caiva yoginaḥ|
prayātā yānti taṃ kālaṃ vakṣyāmi bharatarṣabha||

English translation (above): Shri Purohit Swami (1935), public domain. Sanskrit text via github.com/gita/gita (Unlicense).