after a sale , how long am I obligated to fullfill the deal if not paid?

sorry If this is wrong section. I sold an item..my first one here..and I am still waiting payment. I thought when I agreed to the sale price it mentioned a time frame that I was obligated to complete the sale. maybe I was half asleep. 

anyhow...I havnt been paid and I am not going to wait much longer ..what are my obligations  here? buyer told me he was paying this am and he hasnt contacted me or anything.  I did him earlier but I feel he is stringing me along and i need to move this item.