Reference for Bava Metzia 69:9
אמר רבא הוה יתיבנא קמיה דרב נחמן ופרקין המפקיד הוה ואמרי ליה שילם ולא רצה לישבע ולא אהדר לי
A man once deposited jewels with his neighbour. When he demanded, 'Give me my jewels,' he replied, 'I do not know where I put them.' So he came before R. Nahman, Who said to him: Every [plea of] 'I do not know' is negligence; go and pay. Yet he did not pay, so R. Nahman went and had his house seized. Subsequently the jewels were found, [by which time] they had appreciated. Said R. Nahman: Let the jewels be returned to their [first] owner, and the house to its owner. Raba observed: I was sitting [then] before R. Nahman and it [the subject of our study] was the chapter, 'IF ONE ENTRUSTS [etc.];<span class="x" onmousemove="('comment',' I.e., we were then studying the present chapter. ');"><sup>7</sup></span>