Yoga Sutras of Patanjali · 4.12

अतीतानागतं स्वरूपतोऽस्त्यध्वभेदाद्धर्माणाम्॥१२॥

atītānāgataṁ svarūpato'sty adhvabhedād dharmāṇām

The past and the future exist in their own form; they differ from the present only by the path of dharma — by the mode in which their qualities are arranged.

— Yoga Sutras of Patanjali 4.12

Source: Sanskrit attributed to Patanjali (c. 2nd century BCE – 4th century CE). Public-domain English readings drawn from Swami Vivekananda's 'Raja Yoga' (1896) and Charles Johnston's 'The Yoga Sutras of Patanjali' (1912).