Yes, this is something people are lenient about: lying to children. Lying to children is not permissible; neither to adults nor to children.
Category: Manners
As a father, it is not your job
As a father, it is not your job to remove the thorns from the path of your child – out of fear they may scratch. Indeed the thorns will never cease, and you will not live forever!!
From the mistakes which parents fall into
From the mistakes which parents fall into when uttering wrong words in front of their children, is that they censure the children when they utter them [too]!
Do not supplicate against your children!
Supplicating against the children is wrong!
Teaching precedes disciplining
Many people are overcome with protective jealousy (الغَيْرَة) to start with disciplining before teaching!
How and when do children become a fitnah?
Children are a fitnah, [as Allaah عز و جل says]
Keep a protective eye over your children
Then, as for you O Father! Observe your children[’s activities] – [even] outside the home. Where did they go? Who do they mix with?
Do not be negligent in watching over your children
[And] many of them are very negligent [of their responsibility] towards their children.
Importance of righteous parenting
And indeed, from the greatest reasons for helping to improve the Hereafter of the offspring is the righteousness of the parents; and in other words, [their setting] a good example.
Valuable advice for teachers
O teachers, you have been entrusted with a responsibility.