Ikrimah narrates from Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) that Allah Almighty says: "Allah has pardoned you; why did you give them leave, until it became clear to you who were truthful and you knew the liars?" [Surah al-Tawbah: 43], and "Those who believe in Allah and the Last Day do not ask your leave to be excused from striving with their wealth and their lives, and Allah knows well the God-fearing" [Surah al-Tawbah: 44], and "Only those ask your leave who do not believe in Allah and the Last Day and whose hearts are in doubt, so in their doubt they waver" [Surah al-Tawbah: 45]. These verses were abrogated by the verse of Surah al-Nur: "The believers are only those who believe in Allah and His Messenger, and when they are with him on a matter of common concern, they do not leave until they have asked his permission. Indeed, those who ask your permission are the ones who believe in Allah and His Messenger. So when they ask your permission for some affair of theirs, give permission to whom you will among them, and ask Allah's forgiveness for them. Indeed, Allah is Forgiving, Merciful" [Surah al-Nur: 62]. Qatadah (may Allah have mercy on him) says: Here He granted a concession, after He had said: "Allah has pardoned you; why did you give them leave, until it became clear to you who were truthful and you knew the liars?" [Surah al-Tawbah: 43]
Hadith Referenceالسنن الكبرى للبيهقي / كتاب السير / 18582