Lord Parasumara only established the temple for the first time in sabarimala. At that time he consecrated the idol of Dharma sasths. To kill Mahishi  Dharma sastha incarnated as Ayyappa. After the purpose of the incarnation was completed  the idol of ayyappa with chinmuthra and yoga pattam pose was consecrated. In olden days, worship was done for Sastha only once in a year. Later when Ayyappa idol was consecrated  Performance of the monthly, mandala, makara vilakku poojas commenced. In olden days those who have studied all the four Vedas and puranas, sasthras were hailed as persons who know all the four. Since the He is the son of siva-vishnu who have made the Vedas and puranas, Ayyappa knew all of them by birth itself. Since HE was an incarnation in human form and to that effect was born as the son of Pandalam king, he studied thoroughly all sasthras,Vedas and puranas he was known as one who knows all the foue.