Is it permissible to perform the obligatory prayer without the Iqamah, and what is the Iqamah, and is prayer permissible without it?

The Adhan (call to prayer) is an announcement of the prayer time for those not present, and the Iqamah (call to commence prayer) is an announcement for those present and ready for prayer.

The wordings of the Iqamah are similar to the Adhan, with the addition of "Qad qamati al-Salah" (The prayer has indeed commenced) after "Hayya 'ala al-Falah" (Hasten to success).

The madhhabs (schools of thought) differed regarding the repetition or singularity of the Iqamah's wordings. The majority of scholars hold that its wordings should be recited singularly, with the takbir (Allahu Akbar) at its beginning and end, and "Qad qamati al-Salah" recited twice. They base this on the hadith of Anas: "Bilal was commanded to recite the Adhan with even numbers (repeatedly) and the Iqamah with odd numbers (singly)." Whereas the Hanafis hold that all its wordings should be recited twice, basing this on the hadith of Abdullah ibn Zayd al-Ansari.

The Iqamah is a confirmed Sunnah (Prophetic tradition), and the prayer is valid without it, but it is not permissible to abandon it, as it is one of the manifest rituals of Islam. The proof of its Sunnah status is the hadith of the one who prayed badly, where the Prophet, peace and blessings be upon him, did not mention the Iqamah among what he commanded him to do.