Question Steam voucher wrongly bought - how to sell

[mat257]

Hello everybody.
I m sorry for bothering with this out of thread topic but I ve bought some steam voucher s up to 140 eur but the supposed beneficiary told he is not longer playing games because of time shortage.
How can I sell them?
In. Many second hand items web site (Amazon, eBay , marketplace) , this transaction is forbidden.
Thank you

 

[Aeacus]

Can't you refund it?
Steam gift support: https://help.steampowered.com/en/faqs/view/2C02-3563-B72F-F117
Refund policy: https://store.steampowered.com/steam_refunds