Sunan Ibn Majah 2470
It was narrated from Simak that the heard Musa bin Talhah bin `Ubaidullah narrating that his father said:
“I passed by some palm trees with the Messenger of Allah (ﷺ) and he saw some people  pollinating the trees. He said: 'What are these people doing?' They said: 'They are taking something from the male part (of the plant) and putting it in the female part.' He said: 'I do not think that this will do any good.' News of that reached them, so they stopped doing it, and their yield declined. News of that reached the Prophet (ﷺ) and he said: 'That was only my thought. If it will do any good, then do it. I am only a human being like you, and what I think may be right or wrong. But When I tell you: “Allah (SWT) says,” I will never tell lies about Allah (SWT).' ”
حَدَّثَنَا عَلِيُّ بْنُ مُحَمَّدٍ، حَدَّثَنَا عُبَيْدُ اللَّهِ بْنُ مُوسَى، عَنْ إِسْرَائِيلَ، عَنْ سِمَاكٍ، أَنَّهُ سَمِعَ مُوسَى بْنَ طَلْحَةَ بْنِ عُبَيْدِ اللَّهِ، يُحَدِّثُ عَنْ أَبِيهِ، قَالَ مَرَرْتُ مَعَ رَسُولِ اللَّهِ صلى الله عليه وسلم فِي نَخْلٍ فَرَأَى قَوْمًا يُلَقِّحُونَ النَّخْلَ فَقَالَ ‏"‏ مَا يَصْنَعُ هَؤُلاَءِ ‏"‏ ‏.‏ قَالُوا يَأْخُذُونَ مِنَ الذَّكَرِ فَيَجْعَلُونَهُ فِي الأُنْثَى ‏.‏ قَالَ ‏"‏ مَا أَظُنُّ ذَاكَ يُغْنِي شَيْئًا ‏"‏ ‏.‏ فَبَلَغَهُمْ فَتَرَكُوهُ وَنَزَلُوا عَنْهَا فَبَلَغَ النَّبِيَّ صلى الله عليه وسلم فَقَالَ ‏"‏ إِنَّمَا هُوَ ظَنٌّ إِنْ كَانَ يُغْنِي شَيْئًا فَاصْنَعُوهُ فَإِنَّمَا أَنَا بَشَرٌ مِثْلُكُمْ وَإِنَّ الظَّنَّ يُخْطِئُ وَيُصِيبُ وَلَكِنْ مَا قُلْتُ لَكُمْ قَالَ اللَّهُ فَلَنْ أَكْذِبَ عَلَى اللَّهِ ‏"‏ ‏.‏