Sayyiduna Abu Hurairah (may Allah be pleased with him) said: When the first fruit (of the season) was brought to the Prophet Muhammad (peace and blessings be upon him), he would supplicate: «اللّٰهُمَّبَارِكْلَنَا ........... بَرَكَةٍ» meaning, "O Allah, bless our city, bless our fruits, and grant blessings upon blessings in our mudd and sa’ (measures)." Then, from among the children present at that time, he would give that fruit to the youngest of them.
Hadith Referenceسنن دارمي / من كتاب الاطعمة / 2109
Hadith Takhrijاس روایت کی سند حسن لیکن دوسری سند سے حدیث صحیح ہے۔ دیکھئے: [مسلم 1373] ، [ابن ماجه 3329] ، [ابن حبان 3747]
Brief Explanation
(Commentary on Hadith 2108)
Mudd and sa’ are measures for weighing and measuring. From this hadith, it is established to recite the aforementioned supplication upon the arrival of the first fruits or produce of the harvest. Furthermore, distributing the first fruit among children is also a Sunnah. The same analogy can be applied to the first salary or the first profit.