Bhagavad Gita 8.26
शुक्लकृष्णे गति ह्येते जगत: शाश्वते मते |
एकया यात्यावृत्तिमान्यवर्तते पुन:
Translation
These two types of Shukla and Krishna paths of the world are considered eternal. Among these, through one (Shukla) (the seeker) one achieves non-repetition and through the other (Krishna) one achieves repetition.