The allegation of the anti Ahmadi Muslims is that Ahmadas in one of his writing said that the splitting of the moon happened as a sign during the time of the Prophet Muhammadsaw but he has also written that for him the moon and sun eclipsed and therefore it means he is claiming to be greater. This is an allegation against the Prophetsaw rather than on Ahmadas. Ahmadas did not say his sign was greater nor has anyone ever asked why the Holy Prophetsaw said both would eclipse for the Mahdi as these are his words and should not be accused. No one ever thought that because of this prophecy, the Messiah and Mahdi would be greater than the Holy Prophetsaw either. The hadith which the anti Ahmadis reject is as follows:
حدثنا أبو سعيد الإصطخري ، ثنا محمد بن عبد الله بن نوفل ، ثنا عبيد بن يعيش، ثنا يونس بن بكير عن عمرو بن شمر عنجابر عن محمد بن علي قال : إن لمهدينا آيتين لم تكونا منذ خلق السماوات والأرض ينكسف القمر لأول ليلة من رمضان وتنكسف الشمس في النصف منه ولم تكونا منذ خلق الله السموات والأرض.
For our Mahdi (Spiritual Reformer) there are two Signs which have never occurred before since the creation of the heavens and the earth, namely, the moon will be eclipsed on the first night in Ramadhan (i.e., on the first of the nights on which a lunar eclipse can occur) and the Sun will be eclipsed on the middle day of Ramadhan (i.e., on the middle day on which a solar eclipse can occur) and these Signs have not happened since the creation of the heavens and the earth (Dar Qutni Vol.1, p.188)