Aal-i-Imraan 3:13

There has been a sign for you in the two groups who confronted each other: one fighting for the cause of Allah, and the other disbelievers; they saw them, with their own eyes twice their number[7]. But Allah strengthens with His help whom He wills. There is a lesson in this for those who have insight.

[7] The believers saw the disbelievers to be double their own number preceding the battle of Badr, while, in fact, they were three times their number.

Already there has been for you a sign in the two armies which met [in combat at Badr] - one fighting in the cause of Allāh and another of disbelievers. They saw them [to be] twice their [own] number by [their] eyesight.[118] But Allāh supports with His victory whom He wills. Indeed in that is a lesson for those of vision.

[118] The believers saw the disbelievers to be double their own number preceding the battle of Badr, while, in fact, they were three times their number.

13. There has already been a sign for you (O Jews) in the two armies that met (in combat i.e. the battle of Badr). One was fighting in the Cause of Allâh, and as for the other, (they) were disbelievers. They (the believers) saw them (the disbelievers) with their own eyes twice their number (although they were thrice their number). And Allâh supports with His Victory whom He wills. Verily, in this is a lesson for those who understand. (See Verse 8:44). (Tafsir At-Tabarî)

There was a token for you in two hosts which met: one army fighting in the way of Allah, and another disbelieving, whom they saw as twice their number, clearly, with their very eyes. Thus Allah strengtheneth with His succour whom He will. Lo! herein verily is a lesson for those who have eyes.