Dought & clear, - Shortening the prayers when travelling is a confirmed Sunnah

Is it permissible for a traveller to offer the prayers in full and
pray them with four rak'ahs?
Praise be to Allah.
Shortening the prayers when travelling is a confirmed sunnah that one
should not forsake, according to the consensus of the imams (leading
scholars), apart from what is narrated from ash-Shaafa'i in one of his
two opinions, that offering the prayers in full is preferable. However
the correct view in his madhhab is that shortening the prayers is
preferable.
See:al-Majmoo'by an-Nawawi, 4/218-223
The view that shortening the prayers is preferable is supported by the
fact that the Prophet (blessings and peace of Allah be upon him)
shortened the prayers in all of his journeys, and there is no saheeh
report to indicate that he ever offered the prayer in full when he was
travelling.
Anas ibn Maalik (may Allah be pleased with him) said: We went out with
the Prophet (blessings and peace of Allah be upon him) from Madinah to
Makkah, and he offered his prayers with two rak'ahs every time until
we returned to Madinah.
Narrated by al-Bukhaari, 1081; Muslim, 724.
Ibn 'Umar (may Allah be pleased with him) said: I accompanied the
Messenger of Allah (blessings and peace of Allah be upon him) and
during the journey he did not pray more than two rak'ahs (in any
prayer), and Abu Bakr, 'Umar and 'Uthmaan (may Allah be pleased with
them) did likewise.
Narrated by al-Bukhaari, 1102; Muslim, 689
This refers to the beginning of 'Uthmaan's caliphate; at the end of
his caliphate, 'Uthmaan (may Allah be pleased with him) used to offer
the prayers in full (when travelling).
When 'Abdullah ibn Mas'ood (may Allah be pleased with him) heard that
'Uthmaan ibn 'Affaan (may Allah be pleased with him) was offering the
prayers with four rak'ahs in Mina, he said:Inna Lillaahi wa inna
ilayhi raaji 'oon(Verily to Allah we belong and verily to Him is our
return). I prayed two rak 'ahs with the Messenger of Allah (blessings
and peace of Allah be upon him) in Mina, and I prayed two rak 'ahs
with Abu Bakr al-Siddeeq in Mina, and I prayed two rak 'ahs with 'Umar
ibn al-Khattaab in Mina.
Narrated by al-Bukhaari, 1084; Muslim, 695
Shaykh al-Islam Ibn Taymiyah (may Allah have mercy on him) said:
It is makrooh to offer the prayers in full when travelling. Ahmad
said: I do not like it. It was narrated from Ahmad that he would not
comment on whether offering four rak'ahs would be valid. There is no
sound report to indicate that any of the Sahaabah (may Allah be
pleased with them) used to pray with four rak'ahs when travelling at
the time of the Prophet (blessings and peace of Allah be upon him).
The hadeeth narrated from 'Aa'ishah that suggests something to the
contrary cannot be taken as evidence.
End quote fromal-Ikhtiyaaraat, p. 32
Ibn al-Qayyim (may Allah be pleased with him) said inZaad al-Ma'aad, 1/464:
The Prophet (blessings and peace of Allah be upon him) used to shorten
the four-rak'ah prayers, praying them with two rak'ahs, from the time
he set out travelling until he returned to Madinah. There is no sound
report from him to suggest that he ever offered the four-rak'ah
prayers in full whilst travelling.
With regard to the hadeeth of 'Aa'ishah, according to which the
Prophet (blessings and peace of Allah be upon him) used to shorten the
prayers and offer them in full when travelling, and that he used to
not fast and fast, it is not saheeh. I heard Shaykh al-Islam Ibn
Taymiyah say: This is a lie against the Messenger of Allah (blessings
and peace of Allah be upon him). End quote.
It was narrated that the Prophet (blessings and peace of Allah be upon
him) used to shorten the prayers but 'Aa'ishah would offer them in
full, and he might not fast one day but she would fast.
Our Shaykh Ibn Taymiyah said: This is false. The Mother of the
Believers would not go against the Messenger of Allah (blessings and
peace of Allah be upon him) and all his companions, and pray
differently from them. End quote.
Rather some of the imams, such as Imam Abu Haneefah and Ibn Hazm (may
Allah have mercy on them) were of the view that shortening the prayers
when travelling is obligatory, and it is not permissible to offer them
in full.
However, the correct opinion is that of the majority of scholars, that
shortening the prayers is Sunnah and is preferable, and is not
obligatory. That is supported by the fact that 'Uthmaan and 'Aa'ishah
(may Allah be pleased with them) offered prayers in full when
travelling. If shortening the prayers when travelling was obligatory,
they would not have offered them in full. The Sahaabah followed
'Uthmaan (may Allah be pleased with all of them) in offering the
prayers in full in Mina; if offering the prayers in full was haraam,
they would not have followed him in that.
Imam ash-Shaafa'i (may Allah have mercy on him) said: If it had been
obligatory for the traveller to pray with two rak'ahs, 'Uthmaan,
'Aa'ishah and Ibn Mas'ood would not have offered the prayers in full,
and it would not have been permissible for a traveller to offer the
prayers in full when praying with a resident who is not travelling.
End quote fromal-Umm, 1/159
Shaykh Ibn 'Uthaymeen (may Allah have mercy on him) said inash-Sharh
al-Mumti', 4/358-362:
Some of the scholars said that offering the prayers in full (when
travelling) is makrooh (disliked), because this is contrary to the
regular, ongoing practice of the Prophet (blessings and peace of Allah
be upon him), as the Messenger (blessings and peace of Allah be upon
him) never offered the prayer in full when travelling, and he said:
"Pray as you have seen me praying." This is the view favoured by
Shaykh al-Islam Ibn Taymiyah(may Allah have mercy on him) and it is a
strong view; in fact it may be the strongest of the opinions.
Some of the scholars said that shortening the prayers is obligatory
and that the one who offers the prayer in full is sinning.
What seems to me to be most correct is that offering the prayers in
full (when travelling) is makrooh, not haraam, and that the one who
offers the prayer in full is not sinning. This is from a theoretical
point of view.
But from a practical point of view, is it befitting for a person to do
something when he fears that he may be sinning thereby?
It is not appropriate conduct; rather you should do what is Sunnah,
because that is better for your spiritual wellbeing, even if it is
permissible for you to do something contrary to that. End quote.
Based on that, it is preferable for the traveller to shorten his
prayers, but he does not have the right to refrain from offering the
prayer in congregation for the sake of shortening the prayer; rather
he must offer prayers in congregation. If the imam is a resident (not
travelling), he must offer the prayer in full with him, and if he is
travelling, he must shorten the prayer with him.