I had read a Hadeeth about sneeze, which was as follows: a) When a person sneezes - he says al-Hamdu Lillaah, b) If you have some Du'aa in your heart which you want Allaah to answer, and if you sneeze that time, it is sign that your prayer are accepted. c) If you are having a conversation with some one, and you are in doubt and at that time if you sneeze, it means the person is saying truth. Can please advise whether this Hadeeth is Saheeh, and with reference.

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger. We ask Allaah to exalt his mention as well as that of his family and all his companions.

Saying 'Alhamdu Lillaah' (all perfect praise be to Allaah) after sneezing: The Prophet said: "When a person sneezes he should say, 'Alhamdu Lillaah' (all perfect praise be to Allaah).  His brother or companion should say to him: 'Yarhamukallaah' (May Allaah have mercy upon you). And the one who sneezed should reply back to him: 'Yahdeekumullaahu wa Yuslihu Baalakum' (May Allaah guide you and rectify your condition)." [Al-Bukhari]

There is no authentic narration saying that sneezing when supplicating is an evidence that the supplication is answered. Abu Nu'aym reported that Abu Hurayrah narrated that the Prophet said: "Sneezing when supplicating is a sign that the supplication is answered," but this is a weak narration, and Imaam Al-Albaani said that this is a fabricated narration. Imaam Al-Bayhaqi also reported the following narration: "Sneezing when supplicating is a sign of happiness."

 Some weak narrations have also been reported about the saying that sneezing when having a conversation is an evidence that the speaker is saying the truth. For instance "If someone says a statement and sneezes when he says it, then it is the truth", reported by At-Tabaraani and Al-Bayhaqi who said that it is an objectionable narration. The other narration is: "If a person sneezes when speaking, it means that he is saying the truth". Ibn Al-Qayyim said that this is a weak narration. He also said: 'The senses prove that this is a fabricated narration, because we notice a person sneezes when he lies, and even if one hundred thousand people sneeze when a narration about the Prophet is being reported, this does not prove that it is an authentic narration just because of the sneezing, and if they sneeze when falsely testifying, then this is also not considered as the truth.' A similar narration is: "The most truthful narration is the one to which people sneeze when hearing it." [At-Tabraani] Imaam Al-Albaani said that this is a fabricated narration.

Allaah knows best.