Is it true that whoever prays alone has two angels praying behind him?

If the Sheikh's statement, "If I establish the prayer alone," means that he prays in a wilderness, then this is correct. For Al-Tabarani and others narrated from Salman Al-Farsi, may Allah be pleased with him, that the Prophet, peace and blessings of Allah be upon him, said: "If a man is in a desolate land (i.e., a wilderness) and the time for prayer arrives, let him perform ablution... If he establishes the prayer (i.e., pronounces the Iqamah), his two angels pray with him. And if he gives the call to prayer (Athan) and establishes the prayer (Iqamah), then behind him pray legions of Allah whose ends cannot be seen." This hadith is authentic.

However, if he does not mean a wilderness, but rather prays alone in a populated area, then there is no evidence that the two angels pray with him. But it has been narrated that whoever performs ablution and goes out to the mosque for congregational prayer, and finds that he has missed it, Allah grants him the reward of those who attended it with the congregation, as narrated by Abu Dawud and others.