The Prophet ﷺ was approached while he was at his resting place in Dhul-Hulayfah, in the valley, and was told, "You are in a blessed valley."
أن النبي ﷺ أتي وهو في معرسه من ذي الحليفة في بطن الوادي فقيل: إنك ببطحاء مباركة.
Bukhari narrated it in the Hajj chapter (1535), and Muslim in the Hajj chapter (1346:434), both through the route of Musa bin Uqba, from Salim bin Abdullah bin Umar, from his father, who related it, and the wording given is Muslim's.As for the phrase "a blessed batha," Musa bin Uqba said it is lower than the masjid that lies in the bottom of the valley, midway between it and the qibla.The mu'arras (resting place) mentioned in the hadith is different from the spot where the Messenger of Allah ﷺ prayed on his way to Makkah during the Farewell Hajj. Bukhari narrated it in the Prayer chapter (484), with his chain, from Nafi, that Abdullah bin Ibn Umar informed him that the Messenger of Allah ﷺ used to camp at Zulhulayfa whenever he performed Umrah, and during his Hajj, when he made Hajj, under an acacia tree at the spot where the masjid at Zulhulayfa now stands. Whenever he returned from a military campaign along that road, or from Hajj or Umrah, he would descend into the bottom of a valley, and when he came up out of the bottom of the valley he would halt his mount at the batha on the eastern edge of the valley and rest there until morning. This was not at the masjid built of stone, nor on the hillock on which the masjid stands. There was, at that time, a channel there where Abdullah used to pray, in its bottom, close to where the Messenger of Allah ﷺ used to pray. Later the floodwater carried silt into it, burying the spot where Abdullah used to pray.Bukhari also narrated it in the Umrah chapter (1799), from Ahmad bin Hajjaj, who said, Anas bin Iyad narrated to us, from Ubaydullah, from Nafi, from Ibn Umar, that the Messenger of Allah ﷺ would pray at the Masjid of the Tree whenever he set out for Makkah, and when he returned he would pray at Zulhulayfa in the bottom of the valley, and he would spend the night there until morning.The Masjid of the Tree is the site over which the masjid of the miqat was later built. As for the location of the mu'arras, it is unknown and cannot be identified today. Nafi mentioned that the floodwater had already buried that spot with silt in his own time.See Tarikh al-Kabir (1/415) and (8/85).