Biblical Reference:
The phrase "those who hunger and thirst for righteousness" is prominently found in the Beatitudes, a section of the Sermon on the Mount delivered by Jesus Christ. The specific verse is Matthew 5:6, which states: "Blessed are those who hunger and thirst for righteousness, for they will be filled" .

Context and Meaning:
In the cultural and historical context of the Bible, hunger and thirst are powerful metaphors for deep, essential needs. Just as physical hunger and thirst drive individuals to seek sustenance, spiritual hunger and thirst compel believers to seek righteousness. Righteousness, in this context, refers to a right relationship with God, characterized by living in accordance with His will and commands.

Theological Significance:
The Beatitudes, including the blessing for those who hunger and thirst for righteousness, are foundational teachings of Jesus that outline the values of the Kingdom of Heaven. This particular beatitude emphasizes the importance of a deep, earnest desire for moral and spiritual integrity. It suggests that such a longing is not only commendable but also promises divine fulfillment.

Old Testament Foundations:
The concept of longing for righteousness is deeply rooted in the Old Testament. Psalm 42:1-2 expresses a similar yearning: "As the deer pants for streams of water, so my soul longs after You, O God. My soul thirsts for God, the living God" . This imagery underscores the intensity of the desire for God's presence and righteousness.

New Testament Application:
In the New Testament, the call to pursue righteousness is echoed throughout the epistles. Paul, in his letter to the Romans, writes about the righteousness that comes from faith (Romans 1:17). This righteousness is not self-derived but is a gift from God, attainable through faith in Jesus Christ.

Practical Implications for Believers:
For Christians, hungering and thirsting for righteousness involves a continuous pursuit of holiness and a life that reflects the character of Christ. It requires a commitment to prayer, study of the Scriptures, and active participation in the life of the church. This pursuit is not passive but involves active engagement in spiritual disciplines and a willingness to be transformed by the Holy Spirit.

Promise of Fulfillment:
The promise that "they will be filled" assures believers that their spiritual longing will be satisfied. This fulfillment is both present and future. In the present, believers experience a sense of peace and purpose as they align their lives with God's will. In the eschatological future, the ultimate fulfillment will be realized in the eternal presence of God, where righteousness will be fully and perfectly realized.

Conclusion:
The beatitude of those who hunger and thirst for righteousness calls believers to a life of earnest seeking after God's will and character. It assures them of the profound satisfaction that comes from living in harmony with divine principles, both now and in the life to come.