As for his phrase in the ḥadīth, “munaḥaba,” it denotes a speculative venture—that is, a wager—derived from naḥb (1), meaning a vow. Both carry an element of obligation (2): the former through a contractual commitment, the latter through a vow.
Regarding the words, “Why did you not lower it?” they may derive from khafḍ in the sense of ease and tranquility, meaning: “Could you not have given yourselves more time, so that you would remain at ease and in comfort?”
It may also come from khafḍ in the sense of reduction (3), i.e., “Why did you not persuade them to accept a longer period than the one you agreed on?”
In another wording (4) he says, “Why did you not hedge?”—from iḥtiyāṭ (taking precautions)—that is, “Why did you not choose the safer course and set the deadline at the farthest limit encompassed by al-biḍʿ (‘a few’), since one must not exceed the explicit wording of the text.”
The statement, “That was before wagering was prohibited,” is from one of the narrators (5); it is neither the speech of Abū Bakr nor of the Prophet (6).
Scholars have differed as to whether this ḥadīth remains operative or has been abrogated, falling into two positions.