Saying "Sadaqa Allah-ul-Azhim" upon finishing reciting the Qur’an is a Bid‘ah (innovation in religion). (Part No. 4; Page No. 150) Neither the Prophet (peace be upon him), nor the Rightly-Guided Caliphs, nor the other Sahabah (Companions, may Allah be pleased with them), nor the Imams of the Salaf (righteous predecessors, may Allah be merciful to them) ever said this, although they recited the Qur’an regularly, cared greatly about it, and were knowledgeable about its rules. Therefore, saying these words regularly after concluding recitation of the Qur’an is a Bid‘ah. The Prophet (peace be upon him) is authentically reported to have said:
Anyone who introduces anything into this matter of ours (Islam) that is not part of it will have it rejected.
He (peace be upon him) also said:
Anyone who does an action that is not in accordance with this matter of ours (Islam) will have it rejected.
May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.