Ibn al-Mubarak reported: Maymun ibn Mihran wrote to Yunus ibn Ubaid, may Allah have mercy on him, saying, “I would love for you to write to me about what you do that I might do it.” Yunus wrote back to him, saying, “Verily, I strive for my soul to love for people what it loves for itself, and to hate for people what it hates for itself.”
Al-Halimi, may Allah have mercy on him, said, “It is not befitting for a Muslim to wish evil in his heart for his brother that he would hate for himself, or to hate good that he wishes and loves for himself.”
Source: Shu’ab al-Imān 10379
عَنِ ابْنِ الْمُبَارَكِ قَالَ كَتَبَ مَيْمُونُ بْنُ مِهْرَانَ إِلَى يُونُسَ بْنِ عُبَيْدٍ رَحِمَهُ اللَّهُ إِنِّي أُحِبُّ أَنْ تَكْتُبَ إِلَيَّ بِمَا أَنْتَ عَلَيْهِ لأَكُونَ عَلَيْهِ قَالَ فَكَتَبَ إِلَيْهِ يُونُسُ إِنِّي جَهَدْتُ بِنَفْسِي أَنْ تُحِبَّ لِلنَّاسِ مَا تُحِبُّ لَهَا وَتَكْرَهُ لَهُمْ مَا تَكْرَهُ لَهَا
قَالَ الْحَلِيمِيُّ رَحِمَهُ اللَّهُ وَلا يَنْبَغِي لِمُسْلِمٍ أَنْ يَتَمَنَّى بِقَلْبِهِ لأَخِيهِ مِنَ الشَّرِّ مَا يَكْرَهُ لِنَفْسِهِ أَوْ يَكْرَهُ لَهُ مِنَ الْخَيْرِ مَا يَتَمَنَّاهُ وَيُحِبُّهُ لِنَفْسِهِ
10379 شعب الإيمان للبيهقي