The Quran

يوصيكُمُ اللَّهُ في أَولادِكُم ۖ لِلذَّكَرِ مِثلُ حَظِّ الأُنثَيَينِ ۚ فَإِن كُنَّ نِساءً فَوقَ اثنَتَينِ فَلَهُنَّ ثُلُثا ما تَرَكَ ۖ وَإِن كانَت واحِدَةً فَلَهَا النِّصفُ ۚ وَلِأَبَوَيهِ لِكُلِّ واحِدٍ مِنهُمَا السُّدُسُ مِمّا تَرَكَ إِن كانَ لَهُ وَلَدٌ ۚ فَإِن لَم يَكُن لَهُ وَلَدٌ وَوَرِثَهُ أَبَواهُ فَلِأُمِّهِ الثُّلُثُ ۚ فَإِن كانَ لَهُ إِخوَةٌ فَلِأُمِّهِ السُّدُسُ ۚ مِن بَعدِ وَصِيَّةٍ يوصي بِها أَو دَينٍ ۗ آباؤُكُم وَأَبناؤُكُم لا تَدرونَ أَيُّهُم أَقرَبُ لَكُم نَفعًا ۚ فَريضَةً مِنَ اللَّهِ ۗ إِنَّ اللَّهَ كانَ عَليمًا حَكيمًا

(Saheeh International)

Allāh instructs you concerning your children [i.e., their portions of inheritance]: for the male, what is equal to the share of two females. But if there are [only] daughters, two or more, for them is two thirds of one's estate.¹ And if there is only one, for her is half. And for one's parents, to each one of them is a sixth of his estate if he left children. But if he had no children and the parents [alone] inherit from him, then for his mother is one third. And if he had brothers [and/or sisters], for his mother is a sixth,² after any bequest he [may have] made or debt.³ Your parents or your children – you know not which of them are nearest to you in benefit. [These shares are] an obligation [imposed] by Allāh. Indeed, Allāh is ever Knowing and Wise.

Literally, "that which he left."
Although the siblings themselves do not inherit in this case.
Based upon prophetic ḥadīths, scholars have ruled that debt takes precedent over a bequest, that a bequest may not include any who inherit by law, and that the total bequest may not be more than one third of one's estate. After the fulfillment of debts and bequests (if any), the remainder of the estate is to be divided according to the ordinances in this sūrah.