Commentary of Imam Al-Nawawi on the Hadith
The saying of the prophet – peace be upon him- ‘When he sits between a
her fours parts) mostly its home animal (shu’biha Al-arba) and has
intercourse with her then fatigues her’
In another narration the word ‘Ashu’biha’ is used. The scholars have
disagreed about the intended meaning of ‘shu’biha Al-arba’ (the fours)
for some said that it means the arms and the legs, while others have
said that it refers to the legs and thighs, and other said it means the
legs and the edge of the pubic area. Al-Qadi Ayad chose the meaning of
the four areas surrounding the vagina. The word (Shu’b) means areas, its
singular form being (Shu’bah). As for those who say (Ashba’iha) that is
the plural of the word (Shu’b).
The word Aj-hada-ha (fatigue her) means to plow her, which was also
stated by Al-Khatabi. Others have said it means to make her reach
exhaustion as in the phrase ‘she made him toil and labor till he was
exhausted’. Al-Qadi Ayad – may Allah rest his soul- said ‘Primarily, the
word (Jahada’ha) means that the man exerted his effort working in a
woman, where the word (Juh’d) means energy and refers to motion by
describing the type of work. This is similar to his (the prophet) saying
‘he who plowed her’ meaning he who penetrated her by his motion.
Otherwise, what other fatigue could a man experience because of her, and
Allah knows best.
The meaning of the hadith is that the necessity to wash is not limited
to when semen is ejaculated, rather it is when the penile head (Hash-fa,
lit. "the head of the male member,” i.e. head of the penis) penetrates
the vagina, then it is necessary for the man and the woman to wash.
There is no disagreement on this today, even though there was
disagreement on this by some of the early companions and others later.
However, an agreement was later reached and this is what we have shown
and presented previously.
Our companions have said that if the penile head has penetrated a
woman's anus, or a man's anus, or an animal's vagina or its anus then it
is necessary to wash whether the one being penetrated is alive or dead,
young or old, whether it was done intentionally or absentmindedly,
whether it was done willfully or forcefully. This also applies if the
woman places the male member inside her while the man is asleep, whether
the penis is erect or not, whether the penis is circumcised or
uncircumcised. All these situations require that the person committing
the act and the one the act is committed on must wash themselves, unless
the person committing the act or the person the act is committed on is a
young male or female. In that case it cannot be said that the person
must wash, for they do not have the responsibility, rather it is said
that this person is in a state of impurity. If that person can discern
(the sexual act) then his guardian can command him to wash just as he
commands him to perform the ablution washing for prayers. For if he
prays without washing, his prayer has not been performed correctly;
likewise if he doesn’t wash after he reaches puberty he must be forced
to wash. If he washed as a youth and then reaches puberty, then he does
not have to repeat the washing.
Our companions have said that intercourse occurs when a healthy male’s
penile head completely penetrates (an orifice), as has been unanimously
agreed. Thus, when the penile head has completely disappeared (inside
the orifice), then all the regulations concerning washing apply. It is
unanimously agreed that it is not necessary that the entire penile shaft
penetrate to apply the regulations of washing. If part of the penile
head penetrates, then the regulations of washing are not imposed as is
agreed, except by an odd few of our companions who said that even in
this case all the regulations of washing apply. However, this opinion is
wrong, rejected and abandoned. If the male member was severed and what
remained was less than the length of the penile head, then none of the
washing regulations apply. If the part remaining was equal in length to
the penile head length then that part must completely penetrate for the
regulation of washing to apply. If the part remaining was greater in
length to the penile head length then there are two famous opinions for
our companions. The most correct is that if the portion that penetrates
is equal to the length of the penile head, then the regulations for
washing apply. The other opinion is that none of the regulations for
washing apply until the entire remaining length of the penile shaft
completely penetrates and Allah knows best.
If a man wraps a sheath around his male member and then ejaculates
inside a woman’s vagina, then there are three opinions from our
companions. The most famous is that the man must wash. The second is
that he does not have to wash because he ejaculated inside the sheath.
The third is that if the sheath is thick and prevents climax and wetness
(in the vagina) then washing is not necessary, otherwise it is
necessary and Allah knows best.
If a woman inserts (in her vagina) an animal's penis she must wash, and
if she inserts a detached penis (thakaran maktu-an, lit. "a severed male
member”) there are two opinions; the most correct is that she must
wash.
http://hadith.al-islam.com/Loader.aspx?pageid=261
Some Islamic scholars have ruled that bestiality does not invalidate the hajj or ones fast.



Sunni Imam Abu Bakar al-Kashani (d. 587 H) records in his authority work 'Badaye al-Sanae' Volume 2 page 216:



"If he had sexual intercourse with an animal, that will not make his hajj void"[16]



In Fatawa Qadhi Khan, Page 820, the learned Hanafi scholar Allamah
Hassan bin Mansoor Qadhi Khan sets out those acts that do not invalidate
one's fast, and he includes:



"Sex with animals, dead people and masturbation, does not invalidate one's fast provided ejaculation does not occur"[16]



Fatawa Qadhi Khan, Page 820
http://www.wikiislam.net/w/uploads/2/2e/Fatawa_Qadhi_Khan%2C_Page_820.jpg
Others have said it is halal.
http://www.wikiislam.net/w/uploads/d/dc/Sistani-fatwa.jpg
Sex with animals before the mission (Islam) was wide spread and many
narrations are narrated that it is halal but makrooh (disliked). And on
the compulsory precaution one should abandon this practice that may
cause self harm. And you must admit this to the owner of the sheep and
pay the owner.[17]