Musa b. Talha reported: I and Messenger of Allah ﷺ happened to pass by people near the date-palm trees. He (the Holy Prophet) said: What are these people doing? They said: They are grafting, i. e. they combine the male with the female (tree) and thus they yield more fruit. Thereupon Messenger of Allah ﷺ said: I do not find it to be of any use. The people were informed about it and they abandoned this practice. Messenger of Allah ﷺ (was later) on informed (that the yield had dwindled), whereupon he said: If there is any use of it, then they should do it, for it was just a personal opinion of mine, and do not go after my personal opinion;
but when I say to you anything on behalf of Allah, then do accept it, for I do not attribute lie to Allah, the Exalted and Glorious.

حَدَّثَنَا قُتَيْبَةُ بْنُ سَعِيدٍ الثَّقَفِيُّ، وَأَبُو كَامِلٍ الْجَحْدَرِيُّ - وَتَقَارَبَا فِي اللَّفْظِ وَهَذَا حَدِيثُ قُتَيْبَةَ - قَالاَ حَدَّثَنَا أَبُو عَوَانَةَ عَنْ سِمَاكٍ عَنْ مُوسَى بْنِ طَلْحَةَ عَنْ أَبِيهِ قَالَ مَرَرْتُ مَعَ رَسُولِ اللَّهِ ﷺ بِقَوْمٍ عَلَى رُءُوسِ النَّخْلِ فَقَالَ " مَا يَصْنَعُ هَؤُلاَءِ " . فَقَالُوا يُلَقِّحُونَهُ يَجْعَلُونَ الذَّكَرَ فِي الأُنْثَى فَيَلْقَحُ . فَقَالَ رَسُولُ اللَّهِ ﷺ " مَا أَظُنُّ يُغْنِي ذَلِكَ شَيْئًا " . قَالَ فَأُخْبِرُوا بِذَلِكَ فَتَرَكُوهُ فَأُخْبِرَ رَسُولُ اللَّهِ ﷺ بِذَلِكَ فَقَالَ " إِنْ كَانَ يَنْفَعُهُمْ ذَلِكَ فَلْيَصْنَعُوهُ فَإِنِّي إِنَّمَا ظَنَنْتُ ظَنًّا فَلاَ تُؤَاخِذُونِي بِالظَّنِّ وَلَكِنْ إِذَا حَدَّثْتُكُمْ عَنِ اللَّهِ شَيْئًا فَخُذُوا بِهِ فَإِنِّي لَنْ أَكْذِبَ عَلَى اللَّهِ عَزَّ وَجَلَّ " .