According to mythology, Surya is said to be the father of Saturn. But Shani Dev has a feeling of enmity towards his father Surya. There is mutual opposition in the qualities and characteristics of Sun and Saturn, hence whenever there is a conjunction of Sun and Saturn in the horoscope, then the person gets inauspicious results. https://www.vinaybajrangi.com/blog/conjunction/surya-shani-ke-yuti-ka-labh