Skandapurana 5.257.40

5.257.40

skandhe ca bhagavānbrahmā mastakasthaḥ sadāśivaḥ ..
hṛddeśe ca sthito viṣṇuḥ pucchāgre pannagāstathā .. 39 ..
śakṛtsthā vasavaḥ sarve sādhyā mūtrasthitāstava ..
sarve yajñā hyasthideśe kinnarā guhyasaṃsthitāḥ .. 6.258.40 ..

On your shoulder is the Lord Brahmā; Sadāśiva rests upon your head;
Viṣṇu is situated in the region of your heart, and serpents are at the tip of your tail;
all the Vasus dwell in your dung; the Sādhyas are located in your urine;
all the sacrifices are in the region of your bones; the Kinnaras reside in your secret parts.