श्रीमद्देवीभागवतमहापुराणम्

The passage says this in so many words.

• Devī-bhāgavata Purāṇa · Third Skandha 30.42–43 Cited by A pandit's public claim that Ram ji nowhere performed the puja of Durga ji at Vijayadashami was answered with a photograph of the passage from the Devi Purana

  In Āśvina Rāma worships the Goddess by rule on the mountain and keeps the Navarātra vow with fasting and fire-offering.

  The speaker calls the source the Devī Purāṇa; the passage is in the Devī Bhāgavata.

• Devī-bhāgavata Purāṇa · Third Skandha 30.60 Cited by A pandit's public claim that Ram ji nowhere performed the puja of Durga ji at Vijayadashami was answered with a photograph of the passage from the Devi Purana

  Having completed the vow, Rāma worships Vijayā, gives gifts and sets out on the tenth day.