Luke 16:13 in the World English Bible says:
“No servant can serve two masters, for either he will hate the one, and love the other; or else he will hold to one, and despise the other. You aren’t able to serve God and Mammon.”
The word Mammon is more commonly interpreted as money and here could be understood here from the original as treasure and is a kin to a Hebrew word for support, establish, or trust. So I personally think this could be understood as our trust in savings or retirement. In other words, Mammon is the trust in money for our foundation or for our future. Where should our trust and the foundation of our future be?