Skandapurana 14.32.21

14.32.21

tasya bhakṣyasya gandhena niṣkrānto mūṣako bilāt ..
bhakṣaṇāccāmaro jātastasya vāhyo vyajāyata .. 21 ..

Drawn by the scent of that sweetmeat, a mouse came out from its hole; / and from eating it, he became immortal and became his vehicle.