Praise be to Allah.
It is not permissible to sell part of the sacrificial animal or udhiyah, or to sell all of it, except in cases where it is done in accordance with the purpose of the sacrifice, because what a person has given to Allaah cannot be sold at all.
It says in al-Mughni: It is not permissible to sell any part of it – i.e., the sacrificial animal – but if the butcher is poor and he gives him something because he is poor, in addition to the wages that he gives him, that is permissible, because he is entitled to take some of it because of being poor, not as payment for his work. End quote (3/222)
Shaykh Ibn ‘Uthaymeen said: It is haraam to sell any part of the udhiyah, whether the meat or anything else, even the skin. The butcher should not be given anything from it in partial payment for his work, because that is like selling. (Risaalah Ahkaam al-Hadiy wa’l-Udhiyah)
And he (may Allaah have mercy on him) said: It is not permissible to dispose of it – i.e., the udhiyah – in ways that would prevent going ahead with the sacrifice, such as selling, giving away, giving as a pledge and so on, unless he replaces it with something that serves the purpose pf sacrifice better, not for his own ends. If he selects a sheep for sacrifice then he decides that he wants to keep it for some reason and replaces it with one that is better so that he can keep it, that is not permissible, because he is taking back something that he had set aside for Allaah for his own ends and not for serving the purpose of sacrifice in a better way.
With regard to rams, which are male sheep, the ram should have reached the age of one year in order for it to be permissible as a sacrifice, but the Sunnah shows that it is permissible to sacrifice a jadh’ah. The majority of scholars say that this applies only to jadh’ah of sheep, not of goats. A jadh’ah of sheep is one that is six months old, but the older it is than six months the better, because some of the madhhabs say that jadh’ah means one that is a year old.
The evidence that indicates that the desirable age according to sharee’ah is one year is the marfoo’ hadeeth of Jaabir (may Allaah be pleased with him):
“Do not slaughter anything but a two-year-old animal, unless it is too difficult for you, in which case slaughter a jadh’ah sheep.”
Narrated by Muslim 1963.
The apparent meaning of the hadeeth is that a jadh’ah of sheep is only acceptable if a two-year-old is not available. But the majority of scholars interpreted that as referring to what is mustahabb, and they quoted the following as evidence:
1 – It was narrated from one of the companions of the Prophet (peace and blessings of Allaah be upon him) that “a jadha’h is sufficient for what a two-year-old is sufficient.” Narrated by al-Nasaa’i (4383) and Abu Dawood (2799); classed as saheeh by al-Albaani.
2 – It was narrated that ‘Uqbah ibn ‘Aamir (may Allaah be pleased with him) said: We sacrificed a jadh’ah of sheep along with the Messenger of Allaah (peace and blessings of Allaah be upon him). Narrated by al-Nasaa’i (4382). Its isnaad was classed as qawiy by al-Haafiz in al-Fath, and as saheeh by al-Albaani. See the commentary on Zaad al-Ma’aad (2/317).
It should be noted that the same conditions are stipulated for ‘aqeeqah as for udhiyah: the animal should be free of faults and of the proper age. The evidence for that is qiyaas (analogy), on the basis that both are sacrifices.
Thus it may be known that it is acceptable for you to sacrifice a sheep that has reached the age of six months. And Allaah knows best.