Yahya related to me from Malik thatYahya ibn Said used to say,"Even if someone manages to pray before the time of the prayer haspassed, the time that has passed him by is more important, or better,than his family and wealth."Yahya said that Malik said, "Ifthe time for a prayer comes and a traveller delays a prayer throughneglect or forgetfulness until he reaches his family, he should dothat prayer in full if he arrives within the time. But if he arriveswhen the time has past, he should do the travelling prayer. That wayhe only repays what he owes."Malik said, "This is what Ihave found the people and men of knowledge doing in our community."Malik explained that shafaq was the redness in the sky after the sunhad set, and said, "When the redness has gone then the isha prayer isdue and you have left the time of maghrib."
Arabic/English book reference: Book 1, Hadith 23