Skandapurana 14.30.36

14.30.36

pratīpastatsutaḥ sādhuḥ sarvaśīlavatāṃ varaḥ ..
devāpau ca gate svargaṃ jyeṣṭhabhrātaramagrajam..
saṃtyaktvā jagṛhe rājyaṃ śaṃtanustatsuto'varaḥ .. 36 ..

Pratīpa's son was virtuous, the best of all well-behaved men;
and when Devāpi went to heaven, his younger brother Śaṃtanu,
having superseded the eldest brother, took the kingdom.