[Each member] of Rabban Gamliel’s household would enter [the treasury chamber] with his half shekel between his fingers and throw it before the one withdrawing the terumah. The one withdrawing the terumah would purposely push it into the basket.  The one making the withdrawal did not withdraw the terumah until he had inquired, “Shall I withdraw the terumah?” —- and they had replied to him, “Withdraw! Withdraw! Withdraw!” —- three times.