Muhammad said that Satan touches all human offspring making them cry.
Abu Huraira said, "I heard Allah's Apostle saying, 'There is none born among the off-spring of Adam, but Satan touches it. A child therefore, cries loudly at the time of birth because of the touch of Satan, except Mary and her child." Then Abu Huraira recited: "And I seek refuge with You for her and for her offspring from the outcast Satan" (3.36) Volume 4, Book 55, Number 641:Narrated Said bin Al-Musaiyab:Also, same thing at Volume 6, Book 60, Number 71:, Narrated Said bin Al-Musaiyab:
Muhammad said a child born from a union where a parent said a "phrase," Satan cannot harm the child.
The Prophet said, "If anyone of you, when intending to have a sexual intercourse with his wife, says: 'Bismillah, Allahumma jannibna-sh-shaitan, wa jannibi-sh-shaitan ma razaqtana,' and if the couple are destined to have a child (out of that very sexual relation), then Satan will never be able to harm that child." Volume 8, Book 75, Number 397: Narrated Ibn 'Abbas:
Muhammad said Satan can not impersonate him in a dream.
The Prophet said, "Name yourselves with my name (use my name) but do not name yourselves with my Kunya name (i.e. Abu-l Qasim). And whoever sees me in a dream then surely he has seen me for Satan cannot impersonate me. And whoever tells a lie against me (intentionally), then (surely) let him occupy his seat in Hell-fire." Volume 1, Book 3, Number 110: Narrated Abu Huraira: Also at Volume 8, Book 73, Number 217: Narrated Abu Huraira:
Muhammad said that when praying while standing, Satan puts doubts into the person.
Allah's Apostle said, "When anyone of you stands for the prayers, Satan comes and puts him in doubts till he forgets how many Rakat he has prayed. So if this happens to anyone of you, he should perform two prostrations of Sahu while sitting. Volume 2, Book 22, Number 324: Narrated Abu Huraira:
Muhammad said that Satan can reach into a person's body the same as blood reaches it.
Safiya, the wife of the Prophet told me that she went to Allah's Apostle to visit him in the mosque while he was in Itikaf in the last ten days of Ramadan. She had a talk with him for a while, then she got up in order to return home. The Prophet accompanied her. When they reached the gate of the mosque, opposite the door of Um-Salama, two Ansari men were passing by and they greeted Allah's Apostle . He told them: Do not run away! And said, "She is (my wife) Safiya bint Huyai." Both of them said, "Subhan Allah, (How dare we think of any evil) O Allah's Apostle!" And they felt it. The Prophet said (to them), "Satan reaches everywhere in the human body as blood reaches in it, (everywhere in one's body). I was afraid lest Satan might insert an evil thought in your minds." Volume 3, Book 33, Number 251: Narrated Ali bin Al-Husain: Also, see 254
The preceding Hadith are translated by Sahih Bukhari and are quoted from and online source found at http://www.usc.edu/dept/MSA/fundamental ... h/bukhari/.