Sahih Muslim , Hadith 2361 ⓘ

Musa b. Talha reported: I and Allah's Messenger 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 Allah's Messenger said: I do not find it to be of any use. The people were informed about it and they abandoned this practice. Allah's Messenger (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 صلى الله عليه وسلم بِقَوْمٍ عَلَى رُءُوسِ النَّخْلِ فَقَالَ ‏"‏ مَا يَصْنَعُ هَؤُلاَءِ ‏"‏ ‏.‏ فَقَالُوا يُلَقِّحُونَهُ يَجْعَلُونَ الذَّكَرَ فِي الأُنْثَى فَيَلْقَحُ ‏.‏ فَقَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏"‏ مَا أَظُنُّ يُغْنِي ذَلِكَ شَيْئًا ‏"‏ ‏.‏ قَالَ فَأُخْبِرُوا بِذَلِكَ فَتَرَكُوهُ فَأُخْبِرَ رَسُولُ اللَّهِ صلى الله عليه وسلم 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 ‏"‏ ‏.‏