perch, roost, stay
捿 centers on settling into a place for a while: perching like a bird, roosting, or staying somewhere temporarily.
捿 is a rare character combining 扌 (hand) with 妻 (wife), but the historical development is uncertain. It may have originally expressed the idea of settling or perching, but the exact origin is unclear.
The hand radical 扌 beside 妻 (wife) suggests a hand guiding a wife to settle down and stay, like a bird perching on a branch.
For セイ, imagine a bird saying "say" as it perches: say -> セイ, and the hand helps it stay.