Dought & clear, - [ Prayers] - Rulings and issues about praying on a chair.

During Taraweeh prayer, some worshippers need to sit on a chair. We
know that the rear legs of the chair should be placed in line with the
row if the person is going sit throughout the prayer, but my question
is: how should it be lined up in the following cases:
1- When the person sit on the chair during the standing only
2- When he sits on the chair during bowing, prostration or the tashahhud
3- When he sits on the chair during various parts of the prayer?.
Praise be to Allaah.
Firstly:
Standing, bowing and prostrating are pillars or essential parts of the
prayer. Whoever can do them, it is obligatory for him to do them in
the manner prescribed in sharee'ah. Whoever is not able to do them
because of sickness or old age, it is Sunnah for him to sit on the
ground or on a chair.
Allaah says (interpretation of the meaning):
"Guard strictly (five obligatory) As-Salawaat (the prayers) especially
the middle Salaah (i.e. the best prayer - 'Asr). And stand before
Allaah with obedience [and do not speak to others during the Salaah
(prayers)]"
[al-Baqarah 2:238]
It was narrated that 'Imraan ibn Husayn (may Allaah be pleased with
him) said: I had haemorrhoids so I asked the Prophet(peace and
blessings of Allaah be upon him) about praying. He said: "Pray
standing up; if you cannot, then pray sitting down; and if you cannot,
then pray (lying) on your side." Narrated by al-Bukhaari, 1066.
Ibn Qudaamah al-Maqdisi said:
The scholars are unanimously agreed that if a person cannot stand then
he may pray sitting down.Al-Mughni, 1/443
Al-Nawawi said:
The ummah is unanimously agreed that whoever is unable to stand during
the obligatory prayer may pray sitting, and he does not have to repeat
it. Our companions said: his reward will not be less than the reward
for praying standing, because he is excused. It is proven inSaheeh
al-Bukhaarithat the Messenger of Allaah(peace and blessings of Allaah
be upon him) said: "If a person is sick or travelling, the same reward
will be written for him with regard to what he used to do when he was
not travelling and was healthy."
Al-Majmoo', 4/226
Al-Shawkaani said:
The hadeeth of 'Imraan indicates that it is permissible for one who
has an excuse and cannot stand to pray sitting, and for one who has an
excuse and cannot pray sitting to pray lying on his side.
Nayl al-Awtaar, 3/243
Shaykh al-Islam Ibn Taymiyah said:
The Muslims are agreed that if a worshipper is unable to do some of
the obligatory duties of prayer, such as standing, reciting, bowing,
prostrating, covering the 'awrah, facing the qiblah etc, then what he
is unable to do is waived for him. End quote fromMajmoo' al-Fataawa,
8/437
Based on that, if a person offers an obligatory prayer sitting when he
is able to stand, his prayer is invalid.
Secondly:
It should be noted that if a person is exempted from standing, his
excuse does not make it permissible for him to sit on the chair to bow
and prostrate.
If he is exempted from bowing and prostrating in the proper manner,
that excuse does not make it permissible for him not to stand and to
sit on the chair instead.
The basic principle with regard to the obligatory duties of prayer is
that whatever the worshipper can do, he is obliged to do it, and
whatever he is unable to do, is waived for him.
Whoever is unable to stand, it is permissible for him to sit on a
chair during the standing, and he should bow and prostrate in the
proper manner. If he is able to stand but it is difficult for him to
bow and prostrate, he should pray standing, then sit on the chair when
bowing and prostrating, and he should bend lower for the prostration
than for the bowing.
See also question no. 9307and 36738.
Ibn Qudaamah al-Maqdisi said:
If a person is able to stand but he cannot bow or prostrate, the
standing is not waived for him; he should pray standing and tilt his
head for the bowing, then sit down and tilt his head for the
prostration. This is the view of al-Shaafa'i...
Because Allaah says (interpretation of the meaning):"And stand before
Allaah with obedience" [al-Baqarah 2:238], and the Prophet(peace and
blessings of Allaah be upon him) said: "Pray standing." And because
standing is one of the pillars (essential parts of prayer) for the one
who is able to do it, so he must do it, like the recitation. Being
unable to do other things does not mean that this is waived, as is
also the case if he is unable to recite. End quote fromal-Mughni,
1/44.
Shaykh 'Abd al-'Azeez ibn Baaz (may Allaah have mercy on him) said:
The one who prays sitting on the ground or on a chair must make his
prostration lower than his bowing. The Sunnah is for him to put his
hands on his knees when bowing, and when prostrating the Sunnah is to
put them on the ground if possible; if he cannot do that then he
should put them on his knees, because it was proven that the
Prophet(peace and blessings of Allaah be upon him) said: "I have been
commanded to prostrate on seven bones: the forehead - and he pointed
to his nose - the two hands, the two knees, and the edges of the two
feet (i.e., the toes)."
If a person is unable to do that and prays on a chair, there is
nothing wrong with that, because Allaah says (interpretation of the
meaning):
"So keep your duty to Allaah and fear Him as much as you can"
[al-Taghaabaun 64:16]
and the Prophet(peace and blessings of Allaah be upon him) said: "If I
tell you to do a thing, then do as much of it as you can." Saheeh -
agreed upon.
Fataawa Ibn Baaz, 12/245, 246.
Thirdly:
With regard to the placement of the chair in the row, the scholars
(may Allaah have mercy on them) stated that the one who prays sitting
down should have his posterior in line with the row when he is
sitting, so he should not be in front of the row or behind it at that
point, because that is the place in which the body settles.
SeeAsnaa al-Mataalib, 1/222;Tuhfat al-Muhtaaj, 2/157;Sharh Muntaha
al-Iraadaat, 1/279.
It says inal-Mawsoo'ah al-Fiqhiyyah(6/21):
In order for a person's following the imam to be valid, he should not
stand in front of the imam according to the majority of fuqaha'
(Hanafis, Shaafaa'is and Hanbalis).
How do we know whether he is in front of the imam or not, it is judged
by where the heels are. If they are standing level at the heel and the
toes of the one who is praying behind the imam turn out to be in front
because he has longer feet, that does not matter. With regard to those
who are sitting, it is judged by where the posterior is. And with
regard to those who are praying on their sides, it is judged by their
sides.
If the worshipper is going to pray on the chair from the beginning of
the prayer until the end, then he should make the place where he will
sit level with the row.
If he is going to pray standing, but he will sit on the chair when he
bows and prostrates, we asked Shaykh 'Abd al-Rahmaan al-Barraak about
that, and he said that what matters here is the standing position, so
he should be level with the row when standing.
Based on this, the chair will be behind the row, so it should be
placed in such a manner that it will not disturb worshippers in the
row behind.
And Allaah knows best.