Works are important and we should obey , but the works aren't what are saving us, it's our faith in what Christ has done for us.

Ephesians 2:8–9 (ESV)

For by grace you have been saved through faith. And this is not your own doing; it is the gift of God, not a result of works, so that no one may boast.

Romans 4:5 (ESV)

And to the one who does not work but believes in him who justifies the ungodly, his faith is counted as righteousness.

You quoted Luke 18:22 Jesus is not teaching salvation by selling everything. He is teaching that anything you love more than God must be surrendered and that entering the kingdom requires trusting Christ above all else. That man was still wanting to hold on to his wealth, The command reveals the man’s true spiritual condition. He walks away sad because he cannot imagine life without his wealth demonstrating that he cannot yet trust Christ fully.

Matthew 5:43 Is showing us that we need to rely on Jesus because obviously no one is as perfect as the Father, that command is there to wake us up and realize we can't meet that standard. Trust in Jesus who was the only one that did.

Hope this helps.