This is authentic.

Is it true that when we say bismillah, shaytan becomes as small as a fly? Imam Ahmad recorded in his Musnad, that a person who was riding behind the Prophet said, “The Prophet’s animal tripped, so I said, `Cursed Shaytan.’ The Prophet said, Do not say, ‘Cursed Shaytan,’ for if you say these words, Satan becomes arrogant and says, ‘With my strength I made him fall.’ When you say, ‘Bismillah,’ Satan will become as small as a fly.)

Commentary on Hadeeth | July 26, 2014 10:25 am
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Is this true? Ibn Abbas (ra) is one of the most learned men of the Sahaba (Companions). Prophet Muhammad ((may Peace Be Upon Him)) even prayed for him saying “O Allah, make him acquire a deep understanding of the religion of Islam and instruct him in the meaning and interpretation of things.” He with reference to Surah An-Nur “except only that which is apparent” as Ibn Kathir narrated with a Sahih (authentic) chain of narrators, said it’s “The hand, the ring, and the face.” Abdullah Ibn Omar Ibn Al-Khattab (ra) said “the face and the two hands”. Anas Ibn Malik (ra) said “the hand and the ring”. Ibn Hazm said: “all of this (statements) are in the highest of accuracy. And so are statements by Ali (ra), Aisha (ra), and other Tabi’een”.
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You said that zakat money cannot be given for hajj. But in this hadith of Bukhari it is mentioned that it can be given, according to my understanding,I can be wrong. Please explain this hadith to me.