It's the same word phonetically.
To put something for sale (sail).
If you know most of commerce is done over the sea and the origin of commercial law, it's the same word.

What's the relation between the two images SAIL and SALE?

supratic

Ships (vessels) are governed by the Law of the Sea - Maritime, Admiralty, Merchant Laws
In other words, by the UCC 
https://www.law.cornell.edu/ucc


>• Citizenship • Relationship • Worship •Hardship
• Sponsorship • Scholarship •Championship •Censorship

wow, many ships - even relationship is part of the merchant world so it leads to marriage licenses and certificates? 🤯

>Life Partner: Someone you plan to share life with, as if they are spouses but without being legally married.

>Wife/husband: Legally married, contractual commercial partner.