It is reported from Sayyiduna al-Miqdam bin Ma'dikarib (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "The best food a person eats is the food he eats from the earnings of his own hand, and the Prophet of Allah Dawud (peace be upon him) used to eat from the earnings of his own hand."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الإجارة / 11691
It is narrated from Sayyiduna Abu Hurayrah (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "The recitation of the Zabur was made easy for Dawud (peace be upon him). He would order his mount to be saddled and would finish reciting the whole Zabur before it was saddled, and he ate only from the earnings of his own hands."
Sayyidah Aishah (may Allah be pleased with her) said: The Companions of the Messenger of Allah (peace and blessings be upon him) were people who did their own work. In one narration: they used to work their lands with their own hands. Sayyiduna Khabbab bin al-Aratt (may Allah be pleased with him) said: "I was a blacksmith." Sayyiduna Anas bin Malik (may Allah be pleased with him) said, in the story of Ibrahim, the son of the Prophet (peace and blessings be upon him), that he (peace and blessings be upon him) sent Ibrahim to Umm Sayf, the wife of a blacksmith in Madinah. Sayyiduna Sahl bin Sa'd (may Allah be pleased with him) said, in the story of the pulpit, that the Messenger of Allah (peace and blessings be upon him) sent word to a woman that she should tell her carpenter slave to make a pulpit for him to sit on. It is reported from Sayyiduna Sahl (may Allah be pleased with him) that a woman brought a cloak for the Prophet (peace and blessings be upon him) and said: "O Messenger of Allah (peace and blessings be upon him)! I have made it with my own hand so that I may clothe you in it." Sayyiduna Abu Mas'ud (may Allah be pleased with him) said: There was a man from the Ansar named Abu Shu'ayb, who had a slave who dealt in meat; in one narration the word is butcher. He said: "Prepare food so that I may invite the Messenger of Allah (peace and blessings be upon him)." It is reported from Sayyiduna Ibn Abbas (may Allah be pleased with them both), in the story of the sanctity of Makkah, that Sayyiduna al-Abbas (may Allah be pleased with him) said: "O Messenger of Allah (peace and blessings be upon him)! Except the idhkhir (a grass), for our goldsmiths and for our roofs." He (peace and blessings be upon him) said: "Let the idhkhir be excepted." It is reported from Sayyiduna Ibn Abbas (may Allah be pleased with them both) that the Messenger of Allah (peace and blessings be upon him) had cupping done and gave the cupper his wage; had it been something foul in his view, he would not have given it. All these reports indicate that earning (by such crafts) is permissible.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الإجارة / 11692
It is reported from Abu Majidah (may Allah have mercy on him): I fought with a boy, and I cut off his ear, or he cut off my ear. Abu Bakr (may Allah be pleased with him) came to us, and we were brought before him; we presented our dispute to him, and he sent us to Umar (may Allah be pleased with him). He said: This matter has reached (the level of) retaliation; call a cupper to cut (in retaliation) from him. He said two or three times: I heard the Messenger of Allah (peace and blessings be upon him) say: "I gave my maternal aunt a slave boy as a gift, hoping that she would be blessed in him, and I said to her: Do not hand him over to a cupper, a butcher or a goldsmith."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الإجارة / 11693
This is to be understood as a prohibition of tanzih (discouragement), not of tahrim (unlawfulness), and there is discussion regarding the earnings of the cupper.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الإجارة / 11694
It is reported from Sayyiduna Abdullah (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "Seeking lawful earnings is an obligation after the obligation."
Only Abbad bin Kathir al-Ramli narrated it, and he is da'if (weak). When Yahya bin Yahya (may Allah have mercy on him) was asked about the hadith of Abbad bin Kathir on lawful earnings, "The Messenger of Allah (peace and blessings be upon him) said", he said: If he (really) said it.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الإجارة / 11695