三寸旧城五寸执念
[sān cùn jiù chéng wŭ cùn zhí niàn]
'Three inches of old city, five inches of obsession.' A metaphorical way of describing how strong an infatuation or commitment might be compared to the small size of memories associated with the past ('the old city'). Here the user may express a lingering attachment to their old hometown or a former period in life that's been hard to let go.