Reference for Bava Metzia 190:7
מתיב רבא שאלה ושאל בעליה עמה שכרה ושכר בעליה עמה שכרה ושאל בעליה עמה שאלה ושכר בעליה עמה אע"פ שהבעלים עושין מלאכה במקום אחר ומתה פטור מאי לאו במלאכה אחרת
— No; it means on the same work [as the animal was doing]. Then how can it be elsewhere? — [It means] that he went along breaking up [the ground] ahead of it. But since the second clause refers to [working] near it, it follows that the first clause means [actually] a different work! For the second clause states: If he [first] borrows it [sc. the animal] and then borrows its owner; if he hires it and then hires its owner with it, even if the owner is ploughing at its side, and it perishes, he [the borrower or hirer] is responsible! — I will tell you: Both the first clause and the last refer to the same work; and the first clause teaches something of noteworthy interest, and the second likewise. The first clause teaches something of noteworthy interest: though he [the owner] is actually by its side, but yet engaged on the same work, since the owner was in his service from the time the loan was made, he [the bailee] is not responsible. And the second likewise teaches us something of noteworthy interest: though he [the owner] is by its side, yet since the owner was not in his service from the time of the loan, he is responsible. How so? Now, if you concede that the first clause refers to different work and the second to the same, it is well: that very fact is remarkable.<span class="x" onmousemove="('comment',' That though he is free from responsibility when the owner is in his service even for different work, he is nevertheless liable if he is not in service from the very beginning, even if engaged on the same work at the time of death. ');"><sup>6</sup></span>