So, what God is saying is that for the direct recipients, the graces given are unconditional (“no strings attached”), because they are a direct gift from God to them. However, the recipient cannot just past the gift to others.
Question: Why can’t those who receive your direct graces pass them on to others?
God’s answer:
The option is Mine.
You cannot give what you cannot give.
I do not throw pearls before swine.
Meaning: It is God’s prerogative whether or not to the same shall be given to another person. The recipient can only ask God for the option to share. You cannot give what you cannot give means only God can put the “power behind the words”.
God will not give the gifts to those he considers as swine (those who are unappreciative).