When the iqamah is called, may another prayer be offered

Abu Musa al-Ash'ari narrates: The iqamah was called for the prayer. After that, Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) went to one of the pillars of the mosque and offered two rak'ahs; then he joined the prayer.
Al-Tabarani recorded it in al-Mu'jam al-Kabir, and its narrators are thiqat (trustworthy).

Abdullah bin Abi Musa narrates: Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) came to us (i.e. in the mosque) when the imam had begun leading the Subh prayer. Sayyiduna Abdullah (may Allah be pleased with him) offered two rak'ahs standing by a pillar; he had not yet offered the two rak'ahs of Fajr (i.e. the sunnah).
Al-Tabarani recorded it, and its narrators have been declared trustworthy.

Abu Ishaq narrates: Walid bin Uqbah sent a message to Sayyiduna Hudhayfah (may Allah be pleased with him) and Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him), asking them about offering the prayer on the day of Eid; and the iqamah had been called for the Fajr prayer. After this the narrator related the hadith as before.
The narrator Abu Ishaq did not live in the time of either Sayyiduna Hudhayfah (may Allah be pleased with him) or Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him).

Sayyiduna Abu Musa al-Ash'ari (may Allah be pleased with him) narrates: The Prophet (peace and blessings be upon him) saw a man offering the sunnah of Fajr after the mu'adhdhin had called the iqamah, so he nudged him on the shoulder and said: "Could these not have been offered before this?"
Al-Tabarani recorded it in al-Mu'jam al-Kabir and al-Mu'jam al-Awsat, and its narrators have been declared trustworthy.

Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) narrates: The iqamah was called for the Subh prayer, and I got up to offer the two rak'ahs (sunnah) before the Subh prayer. The Prophet (peace and blessings be upon him) took hold of my hand, pulled me and said: "Will you pray four rak'ahs for the Subh prayer?"
Al-Tabarani recorded it in al-Mu'jam al-Kabir, al-Bazzar recorded something similar, and Abu Ya'la also recorded it; its narrators are thiqat (trustworthy).

Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) narrates: I heard the Prophet (peace and blessings be upon him) say: "There is no prayer for one who enters the mosque while the imam is standing leading the prayer; he should not then pray alone by himself, but should join the prayer behind the imam."
Al-Tabarani recorded it in al-Mu'jam al-Kabir; its chain contains Yahya bin Abdullah al-Babulti, who is da'if (weak).

Sayyiduna Anas (may Allah be pleased with him) narrates: The Prophet (peace and blessings be upon him) came out when the iqamah had already been called for the prayer. He saw some people offering the sunnah of Fajr and said: "Are two prayers being offered together?" Then he forbade offering prayer (or these two sunnah rak'ahs) once the iqamah has been called for the prayer.
Al-Bazzar recorded it; Sharik bin Abi Namir narrated it from Sayyiduna Anas (may Allah be pleased with him). Al-Bukhari (may Allah have mercy on him) said: The more authentic is that it is reported from Sharik from Abu Salamah as a mursal narration. Its chain contains Uthman bin Muhammad bin Uthman bin Rabi'ah, whom Ibn al-Qattan declared da'if (weak); Abd al-Haqq said: Error (wahm) predominates in what he narrates.

Sayyiduna Zayd bin Thabit (may Allah be pleased with him) narrates: The Prophet (peace and blessings be upon him) entered (the mosque) while Sayyiduna Bilal (may Allah be pleased with him) was calling the iqamah for the prayer. The Prophet (peace and blessings be upon him) saw a man offering the two rak'ahs (sunnah) of Fajr and said to him: "Are two prayers being offered together?"
Al-Tabarani recorded it in al-Mu'jam al-Awsat; its chain contains Abd al-Mun'im bin Bashir, who is da'if (weak). I say: The hadith of Sayyiduna Thabit bin Qays (may Allah be pleased with him) will come in the chapter mentioning the times in which prayer is disliked, concerning prayers that have a specific cause, if Allah wills.