Jesus repeated his words in Mark 4:25 (“Whoever has will be given more; whoever does not heave, even what they have will be taken from them.”) in different contexts (Matthew 7:2; 13:12; 25:29; Luke 19:26).
The common thread of meaning concerns faithful use of God’s gifts. God promises to bless faithful Christian management and use of his blessings.
In the context of Mark 4:25, God’s blessings are connected to a faithful use of his word. “Consider carefully what you hear,” he continued. “With the measure you use, it will be measured to you—and even more” (Mark 4:24).
When you and I use God’s word faithfully, we can expect the Holy Spirit to use it to nurture and strengthen our faith, and to increase the fruit of the Spirit (Galatians 5:22-23) in our lives.
On the other hand, when people do not use God’s word by reading it or hearing it, the time will come when it will be taken from them.
All this is reason why Jesus said, “If anyone has ears to hear, let them hear” (Mark 4:23).