Imam Abu Bakr (may Allah have mercy on him) says that in Imam Thawri's narration from Hisham bin Ishaq, these words are present: "Just as you used to offer the Eid prayers." (In the same way, the takbeers will also be recited in the prayer for Istisqa.)
Imam Abu Bakr (may Allah have mercy on him) says that in the narration reported by Yunus and Ma'mar from Imam Zuhri, these words are present: that the Prophet (peace and blessings be upon him) led two rak'ahs (units of prayer).
Hadith Referenceصحيح ابن خزيمه / جماع أبواب صلاة الاستسقاء وما فيها من السنن / 1418