וַיֹּ֣אמֶר שְׁמוּאֵ֔ל הֲל֗וֹא אִם־קָטֹ֤ן אַתָּה֙ בְּעֵינֶ֔יךָ רֹ֛אשׁ שִׁבְטֵ֥י יִשְׂרָאֵ֖ל אָ֑תָּה וַיִּמְשָׁחֲךָ֧ יְהוָ֛ה לְמֶ֖לֶךְ עַל־יִשְׂרָאֵֽל׃
And Samuel said: ‘Though thou be little in thine own sight, art thou not head of the tribes of Israel? And the LORD anointed thee king over Israel;
Read halakhic rulings (Jewish law) on I Samuel 15:17: and classical halakhic sources.