What is the core figurative meaning of the garments in fa-sullī thiyābī min thiyābiki?

Imruʾ al-Qays: Address to Fāṭimah, Parting, and the Arrows of the Eyes (Verses 19–22)

• A literal rule for laundering garments
• Disentangling an emotional relationship
• The price of curtains in a litter
• Counting the banners of two tribes