The Prophet ﷺ said, "Whoever does not give up forged speech and evil actions, Allah is not in need of his leaving his food and drink (i.e. Allah will not accept his fasting.)" (Using translation from Bukhārī 1903)
"إِنَّ الصَّائِمَ إِذَا لَمْ يَدع قَوْلَ الزُّورِ، والْعَمَلَ به، والْجَهْلَ؛ فَلَيسَ لله حَاجَةٌ في أنْ يَدَع طَعَامَه، وَشَرَابَهُ".