Surah Ar-Rum 30:4

فِى بِضْعِ سِنِينَ ۗ لِلَّهِ ٱلْأَمْرُ مِن قَبْلُ وَمِنۢ بَعْدُ ۚ وَيَوْمَئِذٍ يَفْرَحُ ٱلْمُؤْمِنُونَ

Within three to nine years. To Allāh belongs the command [i.e., decree] before and after. And that day the believers will rejoice

Translation: Saheeh International

Tafsir

in a few years bid‘ usually means between three and nine or ten years. So the two armies met again seven years after this former encounter and the Byzantines defeated the Persians. …

Excerpt from Tafsir al-Jalalayn, commentary on 30:4, via Quran.com. The reader has the full commentary and 9 more tafsirs.