Skandapurana 1.4.33.17

1.4.33.17

ityāha bhagavānrudraḥ skandasya prītaye purā..
evameva caturthaṃ ca sthāpitaṃ liṃgamuttamam.. 35.17 ..

Thus the blessed Rudra spoke of old for the delight of Skanda. / In this very way the excellent fourth liṅga was installed;