This hadith is narrated by Jabir through another chain of transmitters but Hammad (one of the narrators) made no mention of the two rak'ahs.
Sahih Muslim Book 7, Hadith 69
← Previous Hadith So and so, have you prayed (two rak'ahs)? He said: No. He (the Holy Prophet) said: Then stand and pray.

Sahih Muslim Book 7, Hadith 68 Next Hadith → Have you observed prayer? He said: No. He (the Holy Prophet) said: Stand and offer the two rak'ahs. According to Qutaiba, the words are:" He said: Offer two rak'ahs."

Sahih Muslim Book 7, Hadith 70