Narrated Ibn `Umar: `Umar bin Al-Khattab fixed a grant of 4000 (Dirhams) for every Early Emigrant (i.e. Muhajir) and fixed a grant of 3500 (Dirhams) only for Ibn `Umar. Somebody said to `Umar, "Ibn `Umar is also one of the Early Emigrants; why do you give him less than four-thousand?" `Umar replied, "His parents took him with them when they migrated, so he was not like the one who had migrated by himself.
Source: sunnah.com
Other translations
Arabic
حَدَّثَنَا إِبْرَاهِيمُ بْنُ مُوسَى، أَخْبَرَنَا هِشَامٌ، عَنِ ابْنِ جُرَيْجٍ، قَالَ أَخْبَرَنِي عُبَيْدُ اللَّهِ بْنُ عُمَرَ، عَنْ نَافِعٍ يَعْنِي، عَنِ ابْنِ عُمَرَ، عَنْ عُمَرَ بْنِ الْخَطَّابِ، رضى الله عنه قَالَ كَانَ فَرَضَ لِلْمُهَاجِرِينَ الأَوَّلِينَ أَرْبَعَةَ آلاَفٍ فِي أَرْبَعَةٍ، وَفَرَضَ لاِبْنِ عُمَرَ ثَلاَثَةَ آلاَفٍ وَخَمْسَمِائَةٍ فَقِيلَ لَهُ هُوَ مِنَ الْمُهَاجِرِينَ، فَلِمَ نَقَصْتَهُ مِنْ أَرْبَعَةِ آلاَفٍ فَقَالَ إِنَّمَا هَاجَرَ بِهِ أَبَوَاهُ. يَقُولُ لَيْسَ هُوَ كَمَنْ هَاجَرَ بِنَفْسِهِ.
sunnah.com