Refrain from (apostēte apo). Second aorist (ingressive) active imperative of aphistēmi of Act 5:37. Do ye stand off from these men. “Hands off” was the policy of Gamaliel.
For if--be (hoti eaṅ̇ēi). 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 ēi, undetermined with prospect of determination. Assuming that it is from men, “it will be overthrown” (kataluthēsetai, first future passive of kataluō, to loosen down like a falling house) as was true of the following of Theudas and Judas the Galilean.