You were to leave your gift in front of the altar while you went to make peace with your brother. After doing that, you could return and offer up your gift.
يَجِبُ أَنْ تَتْرُكَ قُرْبَانَكَ أَمَامَ ٱلْمَذْبَحِ وَتذْهَبَ وَتُصَالِحَ أَخَاكَ ،‏ ثُمَّ تَرْجِعَ وَتُقَرِّبَ قُرْبَانَكَ .‏