Kauthumagrihyasutra 5

Now, the inversion of the expiations: everywhere, repeated use of water. Having completed the Prājāpatya penance and the 'Whatever debt [to Yama]...' [mantra] and offered the ardhyāśabali oblation: if prior to that there is an inversion, he should offer the 'Whatever debt [to Yama]...' [mantra]. When everywhere the clarified butter is not consecrated, having offered even the patron of the sacrifice, there is satisfaction. That sacrifice in which the brahmin receives no sacrificial fee becomes demonic. He who sacrifices without sacrificial firewood falls into hell—both the patron of the sacrifice and the priest. Everywhere, through disregarding the proper time for the oblation, a vipra is a destroyer of the sacrifice; with three [omissions], he is a slayer of a brahmin. Disregarding the time of twilight devotion, a vipra is a destroyer of the celestial light. Everywhere, study during the evening twilight is a destroyer of the Veda. Giving instruction to another caste is the destruction of a guru. Everywhere, one who abandons [his duties] by his own will is a slayer of his ancestors. These are those guilty of major sins; there should be no talking with them, nor should they be greeted with respectful salutation; on the road [one should not] look at their face. If done inadvertently, one should murmur the gāyatrī [verse] eight times.

KauthGS 6: