Skandapurana 2.4.2.p101

2.4.2.p101

tasya puṇyasya viśrāṃtirviṣṇunā na nirūpitā .. 52 .. *
śāligrāmaṃ samabhyarcya śrotriyāya mahāmune ..

the limit of his merit has not been defined by Viṣṇu. (52)
Having worshipped a śālagrāma, O great sage, to a learned brahmin