Ibn 'Abbas reported
When there was a solar eclipse the Messenger of Allah (way peace be upon him) observed eight ruku's and four prostrations (in two rak'ahs). This has been narrated by 'Ali also.
Ibn 'Abbas reported
The Apostle of Allah (ﷺ) observed prayer while it was (solar) eclipse. He recited (the Qur'an in qiyam) and then bowed. He again recited and again bowed. He again recited and again bowed and again recited and again bowed, and then prostrated; and the second (rak'ah) was like this.