1. The time for Salaat al-Kusoof lasts from the beginning of the eclipse until it is over, because the Prophet SAWS (peace and blessings of Allaah be upon him) said: When you see that, then pray. (Agreed upon). According to another hadeeth, If you see anything of that, then pray until it is over. (Reported by Muslim).

2. Salaat al-Kusoof should not be done once the eclipse is over, because the time has gone. If an eclipse ends before one knows about it, one does not have to pray, because the reason for this prayer is no longer there.

3. The way in which Salaat al-Kusoof is done is to pray two Rakahs in which Quraan is recited aloud, according to the correct one out of the two scholarly opinions. In the first Rakah, one should recite al-Faatihah and a long soorah such as Soorat al-Baqarah or the equivalent, then do a long rukoo, then raise one’s head and say, Samia Allaahu liman hamidah, Rabbanaa wa lakal-hamd (Allaah listens to the one who praises Him; our Lord to You be praise) after standing upright, as in other prayers. Then one should then recite al-Faatihah and another long soorah, shorter than in the first recitation, equivalent in length to Soorat Aal Imraan. Then one should do another long rukoo shorter than the first, and when raising one’s head, say, Samia Allaahu liman hamidah, Rabbanaa wa lakal-hamd hamdan katheeran tayyiban mubaarakan fih, mal al-samawaati wa mal al-ard wa mal ma shita min shayin bad (Allaah listens to the one who praises Him; our Lord to You be praise, much good and blessed praise, filling heaven and earth and whatever You will besides that). Then he should do two lengthy sujoods, without making the sitting between them too long. Then one should pray the second rakah like the first, with two long rukoos and two long sujoods, as he did in the first rakah. Then he should recite the Tashahhud and say the salaam.

This is the description of Salaat al-Kusoof as prayed by the Messenger of Allaah SAWS (peace and blessings of Allaah be upon him), as was reported with a number of isnaads. Some of these reports are in al-Saheehayn, including the hadeeth narrated by Aaishah (may Allaah be pleased with her): The sun was eclipsed at the time of the Messenger of Allaah SAWS (peace and blessings of Allaah be upon him), and the Messenger of Allaah SAWS (peace and blessings of Allaah be upon him) went out, stood up and said Takbeer (Allaahu akbar), and the people formed rows behind him. The Messenger of Allaah SAWS (peace and blessings of Allaah be upon him) recited a lengthy recitation and did a lengthy rukoo, then he raised his head and said, Samia Allaahu liman hamidah, Rabbanaa wa lakal-hamd. Then he stood upright and recited another lengthy recitation, shorter than the first. Then he said Allaahu akbar and did another lengthy rukoo, shorter than the first. Then he said, Samia Allaahu liman hamidah, Rabbanaa wa lakal-hamd. Then he did sujood. Then in the second rakah he did likewise, until he had completed four rukoos and four sujoods, and the eclipse was over before he had finished. (Agreed upon).

It is sunnah to pray Salaat al-Kusoof in jamaaah (congregation), because this is what the Prophet SAWS (peace and blessings of Allaah be upon him) did, but it is permissible to pray it individually, as with all other naafil prayers. However, praying it in congregation is better.

It is sunnah for the imaam to address the people after the prayer, and to warn them against negligence and being led astray, and to tell them to make lots of duaa and ask for forgiveness. In al-Saheeh it is narrated from Aaishah (may Allaah be pleased with her) that the Prophet SAWS (peace and blessings of Allaah be upon him) finished his prayer then addressed the people and started by praising Allaah then he said, The sun and the moon are two of the signs of Allaah, and they do not become eclipsed for the death or the birth of anyone. If you see that, then call on Allaah, perform salaah, give charity 

If the prayer ends before the eclipse does, then remember Allaah (dhikr) and call on Him (duaa) until the eclipse ends. The prayer should not be repeated. If the eclipse ends before the prayer, then the prayer should be completed quickly, but it should not be stopped or cut off abruptly, because Allaah says (interpretation of the meaning): and render not vain your deeds [Muhammad 47:33]. The prayer should be at the time of the eclipse, because the Prophet SAWS (peace and blessings of Allaah be upon him) said: until it (the eclipse) is over and he also said, until what you are going through is over

Shaykh al-Islam Ibn Taymiyah said: Sometimes eclipses last for a long time, and sometimes for a short time, depending on how much of the sun or moon is eclipsed. The entire sun or moon may be eclipsed, or only half of it, or one-third. If it is a total eclipse, then the prayer should last long enough for all of al-Baqarah or something of similar length to be recited in the first rakah, and in the next rakah a shorter recitation is made. There are saheeh ahaadeeth narrated from the Prophet SAWS (peace and blessings of Allaah be upon him), as we have mentioned, and it is prescribed to shorten the prayer if the reason for it [i.e., the eclipse] is no longer there. So if it is known that the eclipse will not last for long, or if it started to get less, one should still pray, but the prayer should be shortened. This is the opinion of the majority of scholars, because this prayer is prescribed for a specific reason, and if the reason is no longer there and the eclipse is over, one should not pray.