Luke 16:9

“And I say to you, Make to yourselves friends by means of the mammon of unrighteousness, that, when it shall fail, they may receive you into the eternal dwellings.”

Jesus then presses home the point that like the estate manager they should use wealth at their disposal to make friends, but in their case it should be friends whom they will one day meet in ‘Heaven', that is, ‘in eternal dwellings'. They can do this by providing funds for the spreading of the Good News, and by benefiting the Christian poor, both of which will earn eternal gratitude. Then when they reach Heaven they will be rapturously received by those whom they have helped. (This might serve to confirm the idea of recognition of each other in Heaven). It should be noted that it would hardly achieve this if it was obtained or used dishonestly.

Alternately ‘they' might refer to God and the angelic court (as with ‘we' in Genesis 1:26), but, as it parallels the estate manager making friends by his efforts, we are probably intended to see the same idea here.

‘The mammon of unrighteousness.' This simply means the money normally used by an unrighteous world, indicating that it is what the world in its sinfulness holds as of most importance. It might be seen as confirming that the ‘unrighteous steward' was described as such mainly because he mingled with and traded in an unrighteous world, using that world's methods. It does not mean money obtained by dishonest methods. It is rather worldly money sought for in a sinful world, in contrast with heavenly treasure which those whose hearts are pure seek after.

‘When it shall fail.' One day it will come to an end and it will be useless. Indeed no one can take it with them through death. There are no pockets in a shroud. Thus all its benefits can only apply to this life and for the individual cease as soon as this life is over, as the rich man discovers in the next parable.