Al-Zarkashi reported: Malik ibn Anas, may Allah have mercy on him, said, “Seeking the best option is nine tenths of knowledge.”
Al-Baji said, “Istihsan, as applied by the Maliki scholars, means to seek the opinion that is based on the stronger of two indications in the text.”
Source: al-Baḥr al-Muḥīṭ 2/97
عن الزركشي قَالَ مالك بن أنس رحمه الله تِسْعَةُ أَعْشَارِ الْعِلْمِ الِاسْتِحْسَانُ
وَقَالَ الْبَاجِيُّ مَعْنَى الِاسْتِحْسَانِ الَّذِي ذَهَبَ إلَيْهِ أَصْحَابُ مَالِكٍ هُوَ الْقَوْلُ بِأَقْوَى الدَّلِيلَيْنِ
2/97 البحر المحيط