Skandapurana 1.4.11.159

1.4.11.159

śanideśe madhyarātrau mahīsāgarasaṃgame..
jātījaṃ rāvaṇo liṃgaṃ japannāma sudurjayam.. 13.159 ..

in the land of Saturn, at midnight, at the confluence of the Mahī and the ocean;
Rāvaṇa, a liṅga made of jasmine, reciting the name “Very Difficult to Conquer”;