Refrain from (aposthte apo). Second aorist (ingressive) active imperative of apisthmi of verse Acts 37 . Do ye stand off from these men. "Hands off" was the policy of Gamaliel. For if--be (oti ean--h). Hoti gives the reason for the advice. Gamaliel presents two alternatives in terms of two conditional clauses. The first one is stated as a condition of the third class, ean with the present subjunctive h, undetermined with prospect of determination. Assuming that it is from men, "it will be overthrown" (kataluqhsetai, first future passive of kataluw, to loosen down like a falling house) as was true of the following of Theudas and Judas the Galilean.