SB 6.18.51

nādhauta-pādāprayatā
nārdra-pādā udak-śirāḥ
śayīta nāparāṅ nānyair
na nagnā na ca sandhyayoḥ

na—not; adhauta-pādā—without washing the feet; aprayatā—without being purified; na—not; ardra-pādā—with wet feet; udak-śirāḥ—with the head toward the north; śayīta—should lie down; na—not; aparāk—with the head pointed west; na—not; anyaiḥ—with other women; na—not; nagnā—naked; na—not; ca—and; sandhyayoḥ—at sunrise and sunset.

You should not lie down without having washed both of your feet or without being purified, nor with wet feet or with your head pointed west or north. You should not lie naked, or with other women, or during the sunrise or sunset.