The four rakahs before Zuhr: are they lengthened or shortened?

A man sent a question to Sayyidah Aishah (may Allah be pleased with her): Which prayer was the Prophet (peace and blessings be upon him) most fond of performing regularly? She said: The Prophet (peace and blessings be upon him) used to perform the four rak'ahs before Zuhr regularly, in such a way that he would lengthen the standing in them and perform the bowing and prostration in them in an excellent manner.

Sayyiduna Ibn Umar (may Allah be pleased with them both) used to lengthen the four rak'ahs before Zuhr.

Something similar is reported through another chain.

Sayyiduna al-Hasan bin Ali (may Allah be pleased with him) used to pray the four rak'ahs before Zuhr, lengthening them.

Abu Awn said: If he was quick in recitation, he would recite from the long surahs (al-Tiwal), and if he was slow in recitation, he would recite from the Mi'in (the surahs of about a hundred verses).

Sayyiduna Hudhayfah bin Asid (may Allah be pleased with him) said: I saw Sayyiduna Ali (may Allah be pleased with him), after the sun had passed the meridian, offer four long rak'ahs.

Abd al-Rahman bin Budayl said: The person best acquainted with the affairs of Sayyiduna Abdullah (may Allah be pleased with him) told me that, after the sun had passed the meridian, he used to offer four long rak'ahs in his house; then, when the muezzins called the adhan, he would come out and sit in the mosque until the prayer was started.

Sayyiduna Umar (may Allah be pleased with him) recited Surah Qaf in the four rak'ahs before Zuhr.