Bava Batra 43A

אמאי? נוגעין בעדותן הן!

The Talmud asks: Why is this so? Aren’t partners biased in their testimony, as they jointly own the property in question?

הכא במאי עסקינן ⁠– דכתב ליה: ״דין ודברים אין לי על שדה זו״. וכי כתב לו מאי הוי? והתניא, האומר לחבירו: ״דין ודברים אין לי על שדה זו״; ו״אין לי עסק בה״; ו״ידי מסולקות הימנה ⁠– לא אמר כלום!

The Talmud answers: With what are we dealing here? We are dealing with a case where the partner who is testifying wrote to the other partner: I do not have any legal dealings or involvement with regard to this field, thereby relinquishing his ownership of the field. The Talmud asks: And if he wrote this to him, what of it? But isn’t it taught in a baraita that one who says to another: I do not have any legal dealings or involvement concerning this field, or: I have no dealings with it, or: My hands are removed from it, has said nothing? That is to say, these statements have no legal standing.

הכא במאי עסקינן ⁠– כשקנו מידו. וכי קנו מידו מאי הוי? הרי מעמידה בפני בעל חובו –

The Talmud answers: With what are we dealing here? We are dealing with a case where the one testifying performed an act of acquisition with the other partner. Since relinquishing his share in this fashion is effective, his testimony is no longer biased. The Talmud asks: And if he performed an act of acquisition with the one testifying, what of it? His testimony is still biased, as he is establishing the field before his creditor. Once he transferred his share to his partner, his creditor will now be able to collect from the property that he formerly co-owned, as a creditor can collect from property that a debtor once owned despite the fact that he has relinquished his ownership of it. Since his testimony enables him to repay his debt, it is biased.