Bukhari Volume 6, Book 61, Number 530:
Narrated Abu Mas'ud:
The Prophet said, "If somebody recited the last two Verses of Surat Al-Baqara at night, that will be sufficient for him."
Narrated Abu Huraira: Allah 's Apostle ordered me to guard the Zakat revenue of Ramadan. Then somebody came to me and started stealing of the foodstuff. I caught him and said, "I will take you to Allah's Apostle!" Then Abu Huraira described the whole narration and said:) That person said (to me), "(Please don't take me to Allah's Apostle and I will tell you a few words by which Allah will benefit you.) When you go to your bed, recite Ayat-al-Kursi, (2.255) for then there will be a guard from Allah who will protect you all night long, and Satan will not be able to come near you till dawn." (When the Prophet heard the story) he said (to me), "He (who came to you at night) told you the truth although he is a liar; and it was Satan."
Starting at the beginning, the zakat was called "revenue," not charity. By this time there were only Muslims in Medina, so the order to guard the storehouse means the first Muslims couldn't be trusted.
1) The thief couldn't be Satan, for why would a spirit steal food?
2) Further, why would someone trust a thief or Satan to share Qur'anic insights?
a) The referenced verse (2:255) says that Allah is God and that everything belongs to him. Quoting it makes no sense if Satan is Allah's enemy.
a) Yet by saying that it will protect one from Satan, it no longer makes sense.
4) But speaking of senseless, how can one who told the truth be a liar?