When the Prophet of Allah ﷺ saw the new moon, he said: "a new moon of good and right guidance; a new moon of good and right guidance; a new moon of good and right guidance. I believe in Him Who created you" three times. He would then say: "Praise be to Allah Who has made such and such a month to pass and has brought such and such a month."  

أَنَّ النَّبِيَّ ﷺ كَانَ إِذَا رَأَى الْهِلاَلَ قَالَ هِلاَلُ خَيْرٍ وَرُشْدٍ هِلاَلُ خَيْرٍ وَرُشْدٍ هِلاَلُ خَيْرٍ وَرُشْدٍ آمَنْتُ بِالَّذِي خَلَقَكَ ثَلاَثَ مَرَّاتٍ ثُمَّ يَقُولُ الْحَمْدُ لِلَّهِ الَّذِي ذَهَبَ بِشَهْرِ كَذَا وَجَاءَ بِشَهْرِ كَذَا  

When the Messenger of Allah ﷺ saw the new moon, he turned away his face from it. Abu Dawud said: On this subject there is no tradition which has perfect chain and is sound.  

أَنَّ رَسُولَ اللَّهِ ﷺ كَانَ إِذَا رَأَى الْهِلاَلَ صَرَفَ وَجْهَهُ عَنْهُ