Sunan an-Nasa'i 4479
سنن النسائي#4479SahihIt was narrated from Shu'ban who said:"Abdullah bin Dinr narrated to us, from Ibn'Umar, who said; The Messenger of Allah said; "When two people meet to engage in trade, the transaction between them is not binding until they separate, unless they have chosen to conclude the transaction
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Abu GhuddahSahih
Al-AlbaniSahih
Zubair Ali ZaiIsnaad Sahih
In-book reference: 44:31