Commentary for Bava Batra 63:7

ההוא דאמר לחבריה מאי בעית בהאי ארעא א"ל מינך זבינתה והא שטרא

Nor is their evidence accepted in the <i>Beth Din</i> unless they testify together. R. Nathan, however, says that the evidence of one may be taken on one day and the evidence of the other when he comes on the next day.'<span class="x" onmousemove="('comment',' Thus R. Gamaliel agrees with R. Nathan and R. Eliezer with the anonymous opinion. ');">⁷</span> A certain man said to another, 'What are you doing on this land?' He replied, 'I bought it from you, and here is the deed of sale.'

Rashbam on Bava Batra