Israel Folau has given evidence on the first day of a hearing into his sacking by Rugby Australia for a social media post saying "hell awaits" gay people.

Rugby Australia chief Raelene Castle and Wallabies coach Michael Cheika also gave evidence on Saturday.

The hearing into the sacking of the 30-year-old wing is being held in Sydney in front of a three-member panel. No decision is expected before Monday.

Rugby Australia said it did not expect further witnesses on Sunday.

Folau, who signed a four-year deal with Sydney-based Super Rugby side the Waratahs in March and had a contract with Rugby Australia until 2022, escaped punishment for similar comments last year.

He requested a code of conduct hearing after his dismissal.

Cheika has said Folau, who won 73 caps and was expected to play at this year's World Cup, was unlikely to be selected again.

In addition to his rugby union career, Folau has also played professional rugby league and Australian rules football.

In April, Australian rugby league's governing body ruled out Folau returning to the NRL.