By the mammon of unrighteousness (ek tou mamwna th adikia). By the use of what is so often evil (money). In Matthew 6:24 mammon is set over against God as in Luke 16:13 below. Jesus knows the evil power in money, but servants of God have to use it for the kingdom of God. They should use it discreetly and it is proper to make friends by the use of it. When it shall fail (otan ekliph). Second aorist active subjunctive with otan, future time. The mammon is sure to fail. That they may receive you into the eternal tabernacles (ina dexwntai uma ei ta aiwniou skhna). This is the purpose of Christ in giving the advice about their making friends by the use of money. The purpose is that those who have been blessed and helped by the money may give a welcome to their benefactors when they reach heaven. There is no thought here of purchasing an entrance into heaven by the use of money. That idea is wholly foreign to the context. These friends will give a hearty welcome when one gives him mammon here. The wise way to lay up treasure in heaven is to use one's money for God here on earth. That will give a cash account there of joyful welcome, not of purchased entrance.