´It was narrated that Nubaishah said:` “A man called the Messenger of Allah (ﷺ) and said: ‘O Messenger of Allah, we used to sacrifice the ‘Atirah during the Ignorance days in Rajab,; what do you command us to do?’ He said: “Sacrifice to Allah whatever month it is, do good for the sake of Allah and feed (the poor).’ They said: ‘O Messenger of Allah, we used to sacrifice the Far’ah during the Ignorance days; what do you command us to do?’ He said: ‘For every Sa’imah* (flock of grazing animals), feed the firstborn as you feed the rest of your flock until it reaches an age where it could be used to carry loads, then sacrifice it, and give its meat in charity’ – I** think he said – ‘to the wayfarer, for that is good.’”
Hadith Referenceسنن ابن ماجه / كتاب الذبائح / 3167
1؎: «عتیرہ» is the sacrifice of Rajab, and «فرع» was a custom prevalent in the Age of Ignorance (Jahiliyyah), in which the firstborn offspring of a she-camel would be sacrificed to idols by the polytheists. Some have said that when a person’s herd reached one hundred camels, he would slaughter one offspring, and this was called «فرع». In Islam, this practice was rendered void, and the Prophet (sallallahu alayhi wa sallam) said: “It is better than slaughtering the offspring to let it grow up; when it becomes strong and ready, then slaughter it and feed it to travelers.” Some have said that «فرع» and «عتیرہ» are still recommended (mustahabb), but it should be done for the sake of Allah Ta’ala. From this hadith, the permissibility of «فرع» is derived. In another narration, it is mentioned that when it grows up, it should be given in the way of Allah Ta’ala so that it may be used for riding or carrying loads in jihad.
´It was narrated that Nubaishah said:` "It was said to the prophet: 'During the Jahiliyyah we used to offer the 'Atirah.' He said: 'Slaughter for the sake of Allah, the Mighty and sublime, no matter what month it is; do good for the sake of Allah, the Mighty and sublime, and feed the poor."'
Hafiz Muhammad Ameen
The intended meaning is that virtue is not restricted to any particular month; the poor can be fed at any time. Restricting it to the month of Rajab is not appropriate. To designate any month, day, or time from one’s own side and then consider it obligatory or superior is not correct. The reason for this is that it is neither the right nor the responsibility of any human being to specify particular times, days, or months and years for any act of virtue; rather, the determination of time for virtue is solely the right of Allah Ta‘ala. No one else has the authority to make changes in this regard. Furthermore, it is also necessary that the manner and quantity of virtue be exactly as prescribed by the Shari‘ah. Any excess beyond this will be considered an innovation (bid‘ah) and a human invention.
Source: Sunan Nasa'i: Translation and Benefits by Shaykh Hafiz Muhammad Amin Hafizullah, Page: 4233