Bāhirāyatanaparijānana Sutta [SN 35.112, PTS 4.90]

9.

The Discourse on Fully Understanding the External Sense Bases

112. "Monks, without directly knowing and fully understanding visible forms, without becoming dispassionate towards them and abandoning them, one is incapable of eliminating suffering. Sounds ... odours ... flavours ... tangibles ... Without directly knowing and fully understanding mental phenomena, without becoming dispassionate towards them and abandoning them, one is incapable of eliminating suffering. But, monks, by directly knowing and fully understanding visible forms, by becoming dispassionate towards them and abandoning them, one is capable of eliminating suffering. Sounds ... odours ... flavours ... tangibles ... By directly knowing and fully understanding mental phenomena, by becoming dispassionate towards them and abandoning them, one is capable of eliminating suffering." The ninth.