The allegation of the anti-Ahmadis is that Hadrat Ahmad (as) claimed that the eclipses Allah manifested for his truthfulness were greater than the splitting of the moon. This is a false allegaiton of the anti-Ahmadis. The passage is as follows:
The anti-Ahmadis are so ignorant that they fail to realize that this sign was prophesied by the Prophet Muhammad (sa) and not the Promised Messiah (as). Many shcolars believe in this sign till today and awaited it for the true Imam Mahdi. Some have objected that this is a hadith but they cannot deny that it is attributed to Imam Baqir (rh) who is the grandson of Imam Husain (ra) and son of Zainul Abidin (ra). It was made over 1200 years ago and not first mentioned by Hadrat Ahmad (as). It is also a well known fact that the Imams of the Ahle Bait would narration without the full chain of narration because of their status.
The hadith is in Darul Qutni and 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)
Hadrat Ahmad (as) in the same qaseedah writes:
This shows he (as) is praising the Prophet Muhammad (sa). He (as) also writes in Haqiqatul Wahi :
“Whatever signs appear in my support are, in fact, all miracles of the Holy Prophet (sa)” (Haqiqatul Wahi, Ruhani Khazain, Volume 22, page 469)