Assalaamu alaykum wa rahmatullaahi wa barakaatuhu, Shaykh. Yesterday, while I was praying the Fajr prayer (I was praying seated due to an illness and was bowing and prostrating while seated on a chair), I forgot to do make my prostration lower than my bowing (I strongly felt that it was almost the same). Hence I worried whether my prayer would be valid or not, so I discontinued the prayer and started anew. Did I sin by leaving the prayer? I did not say Tasleem and just left it. Also, my prayer finished one or two minutes after sunrise; is that wrong? May Allaah reward you, Shaykh.

All perfect praise be to Allah, The Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.

First of all, it is impermissible to nod the head for prostration in prayer if you are physically able to prostrate on the ground. If you nod, then your nodding for the prostration should be lower than for bowing to the best of your ability. Allah, The Exalted, says (what means): {So, fear Allah as much as you are able.} [Quran 64:16]

Secondly, if you suffer from Waswasah (obsessive doubts), you must ignore it. If you abruptly left the prayer because of Waswasah and you were not certain of missing an obligation, which is nodding lower for the prostration, then you were wrong for doing that. The best remedy for Waswasah is to ignore it completely.

Thirdly, if you were certain that you did not prostrate as required, then you should have repeated the prostration and then complete the prayer and perform two prostrations of forgetfulness (Sujood as-Sahw) at the end of the prayer. You should not have abruptly left your prayer.

Fourthly, since you abruptly ended the prayer before completing it and then repeated it, you have cleared yourself of your liability from the obligation. If you performed a complete unit of prayer of the Fajr prayer before sunrise, then you successfully performed the Fajr prayer at its due time; otherwise, it is regarded as "missed" and you made up for it.

Fifthly, if the praying person abruptly leaves the prayer before completing it in a case in which one is allowed to end it, he bears no sin for ending the prayer without saying Tasleem.

Allah knows best.