"When we were in Jam (Al-Muzadalifah), Ibn Masud said: 'I heard the one to whoem surat Al-Baqarah was revealed say, in this place: Labbaik Allahumma Labbaik." (Using translation from Nasāʾī 3046)
سَمِعْتُ الَّذِي أُنْزِلَتْ عَلَيْهِ سُورَةُ الْبَقَرَةِ يَقُولُ فِي هَذَا الْمَكَانِ لَبَّيْكَ اللهُمَّ لَبَّيْكَ