In most of the Islamic countries, dead bodies are taken to grave in casket on shoulders of four persons, who may change in between. Some people say, husband of a deceased woman cannot give shoulder to his dead wife's casket, according to some Hadeeth. Is this true? If so, then what is the logic behind this?

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.

We do not know an authentic or even a weak narration which says that a husband is not allowed to lift the coffin of his dead wife. No scholar has mentioned this. Imaam Al-Bukhari and Muslim reported that 'Aa'ishah narrated that the Prophet said to her: "What do you think if you die before me, then I will wash you, enshroud you, pray on you and bury you?" This is a clear evidence that a husband can take care of burying his wife, and carrying the corpse is included in the funeral. 

Allaah knows best.