Reference for Pesachim 62:9
אמר ליה רב אחא בריה דרב יוסף לרב אשי הא דאמר שמואל כספים אין להם שמירה אלא בקרקע מי בעינן שלשה טפחים או לא אמר ליה הכא משום ריחא בעינן שלשה טפחים התם משום איכסויי מעינא הוא ולא בעי שלשה וכמה אמר רפרם בר פפא מסיכרא טפח:
A Tanna taught: How far is the searching of a dog? Three handbreadths.<span class="x" onmousemove="('comment',' The leaven must be covered by not less than three handbreadths of debris; otherwise a dog can search it out, and it would therefore be necessary to remove the debris and destroy the leaven.');"><sup>15</sup></span> R'Aha the son of R'Joseph said to R'Ashi: As to what Samuel said, Money can only be guarded [by placing it] in the earth<span class="x" onmousemove="('comment',' That is the only way in which a bailee can carry out his charge; otherwise he is guilty of negligence and liable for theft. - In ancient days there was probably no other place as safe, but nowadays it suffices if the bailee puts the money in the place where he keeps his own (Asheri, B.M. 42a) .');"><sup>16</sup></span>