In the victory of Allah. He gives victory to whom He wills, (30:5)

Almuntakhab Fi Tafsir Alquran Alkarim

The Romans -Christians- have been defeated (by the Persians) - Atheists-, in the land near by - (the near end of the Roman Empire, Syria). but the tide of battle shall turn and following their defeat shall victory and fortune sit on their helm, in some few years from hence. to Allah alone. The Ultimate Authority, are committed and submitted all matters and all affairs for consideration, decision and execution in the beginning and the end, past, present and time to come; there and then shall the Muslims rejoice beyond a common joy for the victory of the Romans. Allah gives mastery and triumph to whom. He will and He is AL-Aziz and AL-Rahim (the Almighty and the Merciful)

Tafseer Tafheem-ul-Quran by Syed Abu-al-A'la Maududi

(30:5) at the victory granted by Allah. *3 He grants victory to whomsoever He pleases. He is the Most Mighty, the Most Compassionate.

In the victory of Allah. He gives victory to whom He wills, meaning

*3) Ibn 'Abbas, Abu Said Khudri, Sufyan Thauri;, Suddi and others have stated that the Romans' victory against the Iranians and the Muslims' victory at Badr against the polytheists took place almost at the same time. The Muslims, therefore, were doubly pleased. The same is supported by the histories of Byzantium and Iran. 624 A.D. is the year in which the Battle of Badr was fought and the same is the year in which the Byzantine Emperor destroyed the birth-place of Zoroaster and ravaged the principal fire-temple of Iran.
 

In the victory of Allah. He gives victory to whom He wills, meaning in Urdu

اللہ نصرت عطا فرماتا ہے جسے چاہتا ہے، اور وہ زبردست اور رحیم ہے