Bhagavatapurana 9.22.19

9.22.19

śalaśca śāntanorāsīdgaṅgāyāṃ bhīṣma ātmavān /
sarvadharmavidāṃ śreṣṭho mahābhāgavataḥ kaviḥ //

19. & 20. Santanu had by Ganga a son called Bhishma who, possessed of self-control, was foremost among those who knew dharma; he, a great devotee of Sri Hari, a wise and learned man, also the foremost warrior by whom even Parasurama was gratified in the art of fighting. Santanu had by a fisher-woman a son called Chitrangada.