Juz 21 of the Quran includes parts of Surah Al-Ankabut (29:46) to Surah Al-Azhab (33:30). This section covers various themes such as the struggle of faith, the importance of trust in God, and the roles and responsibilities within the Muslim community.

Surah Al-Ankabut continues with exhortations to the believers to debate with the People of the Book in the best manner and to persevere in their faith despite hardships. It highlights the story of Prophet Ibrahim (Abraham) and the tests he faced, reinforcing the message of steadfastness in faith.

Surah Ar-Rum (The Romans) predicts the victory of the Romans over the Persians, which serves as a sign of God's power and the fulfillment of His promises. This surah emphasizes the signs of God in nature, history, and within the human self, urging believers to reflect on these signs and recognize the truth of the divine message. It also discusses the inevitability of the Day of Judgment and the resurrection.

Surah Luqman contains the wise advice of Luqman to his son, focusing on the importance of monotheism, gratitude to parents, prayer, humility, and moral conduct. The surah stresses the importance of wisdom and good counsel in guiding oneself and others.

Surah As-Sajda (The Prostration) emphasizes the significance of revelation and the resurrection. It describes the believers who humble themselves in prayer and are steadfast in their faith, promising them eternal rewards.

Surah Al-Ahzab (The Confederates) addresses the events surrounding the Battle of the Trench, highlighting the bravery and unity of the Muslim community in the face of overwhelming odds. It also lays down guidelines for the conduct of the Prophet's wives and underscores the importance of their exemplary behavior for the entire Muslim community.

Juz 21 concludes with a call for the believers to maintain their trust in God, adhere to His guidance, and strive for unity and righteousness within the community.