He prayed Taraaweeh before ‘Isha’!

I entered the masjid late for taraweeh and I missedsix rakahs. after
the taraweeh I prayed the four rakah of isha that I missed. do I have
to pray the six rakahs that I missed of the taraweeh?.
Praise be to Allaah.
It is not correct to pray Taraaweeh and then 'Isha'. You could have
joined the congregation with the intention of praying 'Isha', then
when the imam said the tasleem after the two rak'ahs, you could stand
up and complete the last two rak'ahs. You cannot pray qiyaam before
'Isha', rather it should be done afterwards, and after the regular
Sunnah of 'Isha'. The prayers that you did were simply voluntary
prayers and not qiyaam.
Shaykh 'Abd al-'Azeez ibn Baaz was asked:
If a Muslim comes to the mosque and finds the congregation praying
Taraaweeh and he has not yet prayed 'Isha', should he pray with
them,with the intention of praying 'Isha'?
He replied:
There is nothing wrong with his praying with them with the intention
of praying 'Isha', according to the more correct of the two scholarly
views. When theimam says the tasleem heshould stand up and complete
his prayer. It was proven in al-Saheehayn from Mu'aadh ibn Jabal that
he used to pray 'Isha', then he would go back to his people and lead
them in 'Isha' prayer, and the Prophet (peace and blessings of Allaah
be upon him) did not denounce that. This indicates that it is
permissible to offer a fard prayer behind someone who is praying a
naafil prayer. In al-Saheeh it is also narrated that in the fear
prayer, the Prophet (peace and blessings of Allaah be upon him) led
one group in praying two rak'ahs then he said the tasleem and led the
other group in praying two rak'ahs, then he said the tasleem, so the
first one was his fard (obligatory) prayer and the second was naafil
for him whilst they were praying fard. And Allaah is the source
ofstrength.
Majmoo' Fataawa al-Shaykh Ibn Baaz, 12/181
And the Shaykh also said:
The Sunnah is to pray tahajjud – in Ramadaan and at other times –
after the regular Sunnah of 'Isha', as the Prophet (peace and
blessings of Allaah be upon him) used to do that. It makes no
difference if the tahajjud is done in the mosque or at home.
Majmoo' Fataawa al-Shaykh Ibn Baaz, 11/368
With regard to the Taraaweeh prayers that you have missed, you have
the choice. If you want you can do them and if you want you can leave
them. Taraaweeh is a naafil prayer, so you do not have to make it up
as is the case with the five daily prayers.
And Allaah knows best.