"Melzar, though fearful that by complying with this request he would incur the displeasure of the king, nevertheless consented; and Daniel knew that his case was won. At the end of the ten days’ trial the result was found to be the opposite of the prince's fears. “Their countenances appeared fairer and fatter in flesh than all the children which did eat the portion of the king's meat.” In personal appearance the Hebrew youth showed a marked superiority over their companions. As a result, Daniel and his associates were permitted to continue their simple diet during their entire course of training. PK 484.1"
"And at the end of ten days their countenances appeared fairer and fatter in flesh than all the children which did eat the portion of the king’s meat."
EGW directly quotes and elaborates on Daniel 1:15.
"For three years the Hebrew youth studied to acquire “the learning and the tongue of the Chaldeans.” During this time they held fast their allegiance to God and depended constantly upon His power. With their habits of self-denial they united earnestness of purpose, diligence, and steadfastness. It was not pride or ambition that had brought them into the king's court, into companionship with those who neither knew nor feared God; they were captives in a strange land, placed there by Infinite Wisdom. Separated from home influences and sacred associations, they sought to acquit themselves creditably, for the honor of their down-trodden people, and for the glory of Him whose servants they were. PK 484.2"
"As for these four children, God gave them knowledge and skill in all learning and wisdom: and Daniel had understanding in all visions and dreams."
EGW expands on the idea of the Hebrew youth's learning and dependence on God, which is mentioned in Daniel 1:17.
"The Lord regarded with approval the firmness and self-denial of the Hebrew youth, and their purity of motive; and His blessing attended them. He “gave them knowledge and skill in all learning and wisdom: and Daniel had understanding in all visions and dreams.” The promise was fulfilled, “Them that honor Me I will honor.” 1 Samuel 2:30 . As Daniel clung to God with unwavering trust, the spirit of prophetic power came upon him. While receiving instruction from man in the duties of court life, he was being taught by God to read the mysteries of the future and to record for coming generations, through figures and symbols, events covering the history of this world till the close of time. PK 484.3"
"Wherefore the Lord God of Israel saith, I said indeed that thy house, and the house of thy father, should walk before me for ever: but now the Lord saith, Be it far from me; for them that honour me I will honour, and they that despise me shall be lightly esteemed."
Ellen White directly references 1 Samuel 2:30 in this passage.