In Shiva Purana chapter nineteen (Description of Shiv’s sports) Brahma stared at Sati.

45. Why did Brahma stare at Sati lustfully? More-over he has corpmitted a sin by discharging his emen. Hence I shall kill him.

In chapter twenty (Sati's marriage festival) Siva said to Brahma:

14. In this very form (of a bull) whereon I sit, you shall perform penance with pleasure in your heart and desire for propitiating me.
15. You will acquire the glory of being called "The head of Rudra" in the world. You will be the accomplisher of rites for brahmins of great repute.

(In verses 8 and 9 Brahma said before 8. On hearing these words of Lord Siva adept in divine sports I touched my head and in the same manner bowed to Siva. 9. When I thus touched my head I assumed the shape of his vehicle, the bull.)

Can anyone explain the meaning in easy words to me?

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