Praise be to Allaah.
Yes, it is mustahabb to pray four rak’ahs before Zuhr prayer
and four after it. Al-Nasaa’i (1817) and al-Tirmidhi (428) narrated from Umm
Habeebah (may Allaah be pleased with her) that the Prophet (peace and
blessings of Allaah be upon him) said: “Whoever prays four (rak’ahs) before
Zuhr and four after it, the Fire will not touch him.”
The version narrated by al-Tirmidhi says: “Whoever regularly
performs four rak’ahs before Zuhr and four after it, Allaah will forbid him
to the Fire.”
The hadeeth was classed as saheeh by al-Albaani in Saheeh
al-Nasaa’i.
These rak’ahs are not something different than the regular
Sunnah (Sunnah raatibah) of Zuhr prayer, rather they are the regular
Sunnah.
But what is certain and should not be abandoned under any
circumstances is praying four rak’ahs before Zuhr and two rak’ahs after it.
As for doing four rak’ahs after it, if a person does that following this
hadeeth, then he has done the Sunnah and Allaah will reward him, but if he
limits it to two rak’ahs, that is sufficient.
The time for offering the Sunnah prayer before Zuhr is
between the adhaan of Zuhr and the obligatory prayer.
The time for offering the Sunnah prayer after Zuhr is from
after Zuhr prayer until the adhaan of ‘Asr.
And Allaah knows best.