Hadith #2431 (Sunan Abi Dawud)
Book: Fasting (Kitab Al-Siyam)
Narrator(s): Harun bin Salman هارون بن سلمان, Muhammad bin 'Uthman bin Kramh محمد بن عثمان بن كرامة, Ubaidullah bin Musa bin Abi al-Mukhtar عبيد الله بن موسى بن أبي المختار باذام
Grade: Sahih

The month most liked by the Messenger of Allah (ﷺ) for fasting was Sha’ban. He then joined it with Ramadan.

Source: https://parallelquran.com/hadith/sunan-abi-dawud-2431/