Allah's statement,

وَإِذْ يُرِيكُمُوهُمْ إِذِ الْتَقَيْتُمْ فِي أَعْيُنِكُمْ قَلِيلاً ...

And (remember) when you met, He showed them to you as few in your eyes,

demonstrates Allah's compassion towards the believers. Allah made them see few disbelievers in their eyes, so that they would be encouraged and feel eager to meet them.

Abu Ishaq As-Subai`i said, that Abu Ubaydah said that Abdullah bin Mas`ud said,

"They were made to seem few in our eyes during Badr, so that I said to a man who was next to me, `Do you think they are seventy?'

He said, `Rather, they are a hundred.'

However, when we captured one of them, we asked him and he said, `We were a thousand.'''

Ibn Abi Hatim and Ibn Jarir recorded it.

Allah said next,

... وَيُقَلِّلُكُمْ فِي أَعْيُنِهِمْ ....

and He made you appear as few in their eyes,

According to Ikrimah, as recorded by Ibn Abi Hatim,

Allah said, وَإِذْ يُرِيكُمُوهُمْ إِذِ الْتَقَيْتُمْ (And (remember) when you met. He showed them to you...),

He encouraged each of the two groups against the other.

This statement has a Sahih chain of narrators.

.. لِيَقْضِيَ اللّهُ أَمْرًا كَانَ مَفْعُولاً وَإِلَى اللّهِ تُرْجَعُ الأمُورُ ﴿٤٤﴾

so that Allah might accomplish a matter already ordained, and to Allah return all matters (for decision).

Muhammad bin Ishaq said that Yahya bin Abbad bin Abdullah bin Az-Zubayr narrated to him that his father said about Allah's statement, لِيَقْضِيَ اللّهُ أَمْرًا كَانَ مَفْعُولاً (so that Allah might accomplish a matter already ordained),

"In order for the war to start between them, so that He would have revenge against those whom He decided to have revenge (pagans), and grant and complete His favor upon those He decided to grant favor to, His supporters.''

The meaning of this, is that Allah encouraged each group against the other and made them look few in each other's eyes, so that they were eager to meet them. This occurred before the battle started, but when it started and Allah supported the believers with a thousand angels in succession, the disbelieving group saw the believers double their number.

Allah said,

قَدْ كَانَ لَكُمْ ءَايَةٌ فِي فِئَتَيْنِ الْتَقَتَا فِئَةٌ تُقَـتِلُ فِى سَبِيلِ اللَّهِ وَأُخْرَى كَافِرَةٌ يَرَوْنَهُمْ مِّثْلَيْهِمْ رَأْىَ الْعَيْنِ وَاللَّهُ يُؤَيِّدُ بِنَصْرِهِ مَن يَشَآءُ إِنَّ فِى ذَلِكَ لَعِبْرَةً لاوْلِى الاٌّبْصَـرِ

There has already been a sign for you (O Jews) in the two armies that met (in combat, the battle of Badr). One was fighting in the cause of Allah, and as for the other, (they) were disbelievers. They (disbelievers) saw them (believers) with their own eyes twice their number. And Allah supports with His aid whom He wills. Verily, in this is a lesson for those who understand. (3:13)

This is how we combine these two Ayat, and certainly, each one of them is true, all the thanks are due to Allah and all the favors are from Him.