"The month which the Messenger of Allah most liked to fast was Shaban; indeed he used to join it to Ramadan." (Using translation from Nasāʾī 2350)
أَنَّهُ سَمِعَ عَائِشَةَ تَقُولُ «كَانَ أَحَبَّ الشُّهُورِ إِلَى رَسُولِ اللهِ ﷺ أَنْ يَصُومَهُ شَعْبَانُ كَانَ يَصِلُهُ بِرَمَضَانَ»