"The Messenger of Allah ruled that pre-emption is to be given in everything that is shared in which the division is not clear, whether it is a house or a garden. It is not permissible to sell it before informing one's partner, who may take it or leave it, as he wishes. He (the share-owner) sells it without informing him, and then he has more right to it."  

قَضَى رَسُولُ اللَّهِ ﷺ بِالشُّفْعَةِ فِي كُلِّ شَرِكَةٍ لَمْ تُقْسَمْ رَبْعَةٍ وَحَائِطٍ لاَ يَحِلُّ لَهُ أَنْ يَبِيعَهُ حَتَّى يُؤْذِنَ شَرِيكَهُ فَإِنْ شَاءَ أَخَذَ وَإِنْ شَاءَ تَرَكَ وَإِنْ بَاعَ وَلَمْ يُؤْذِنْهُ فَهُوَ أَحَقُّ بِهِ