Skandapurana 6.3.103.15

6.3.103.15

atha putrasya pautreṇa pragacchedbrahma śāśvatam .
nāsti putrasamo bandhuriha loke paratra ca .. 103.15 ..

and by the grandson of a son one goes to the eternal Brahman. / There is no friend equal to a son, both in this world and in the next.